A thousand times a year, Prince Charles plunges into crowds, tours factories and schools, moves along receiving lines and works receptions like a skillful politician hungry for votes. Annoyance shows only when he is jostled or grabbed.When asked what he will do until he becomes king, he often answers, "I work bloody hard right now."

As part of that work, Charles arrives at Andrews Air Force Base today for a weekend visit to the U.S. As President Ronald Reagan and a select group of Washingtonians will discover, he at first appears surprisingly short and slight in one of the plainly tailored gray suits he favors when not in military uniform. His face is a flushed pink, his large ears protrude from under relatively close-cropped dark hair and his arresting blue eyes draw attention from a prominent nose once broken in a schoolboy rugger game. His thick, rough-skinned hands provide a clue to the hidden strength in his arms and legs and his physical derring-do in the air, on the sea and on horseback.

Only the constant fidgeting of those hands -- one jamming into his coat pocket, the other fingering his breast pocket hankerchief; or one grasping the other behind his back; or turning with his right hand the small gold signet right on his left little finger; or both hands slicing the air in front of him -- reveals the lifelong protective shyness hidden by his ease of conversation with strangers. His handshake is firm, and his eyes meet and hold those of each person he greets as though they were in intimate conversation rather than in the eye of the human hurricane that moves with him everywhere.

He enjoys Americans because they usually are less awed than others and more likely actually to talk to him.In meeting people, he said recently, "you have to get through a certain amount of anxiety or nervousness to start with. After 20 minutes or so, people are beginning to relax and maybe beginning to realize that you are vaguely human, that you actually talk reasonably and are not totally from a different world. Then you have to go."

Charles is the most popular member of the British royal family after his mother, 55-year-old Queen Elizabeth II, and his grandmother, 80-year-old Queen Mother Elizabeth. He is more at ease in public than the queen and much better tempered, polite and patient about public appearances than his outspoken father, Prince Philip, or his sometimes petulant sister, Princess Anne. His younger brothers, Andrew, 21, and Edward, 17, are only now emerging into the limelight. Prince Andrew, tall and strikingly handsome, enjoys much more of the devil-may-care, dashing, privileged young bachelor's life that Prince Charles has, somewhat misleadingly, been identified with.

Although strict protocol dictates that he be addressed as "sir" or "your royal highness," he accepts being referred to as "you." He can shock listeners by casually referring to the queen as "my mother." He seems to enjoy bantering with reporters he encounters in public, although he grants very few interviews and turns aside what he regards as inappropriate questions, particularly those touching on politics. At a recent dinner with American correspondents in London, he answered most questions about himself rather frankly, knowing that Buckingham Palace ground rules prohibited quotation. 'Being Different'

Prince Charles' family broke with tradition to send him out of the palace to school, but he was often as lonely figure at the elite private schools to which he was sent. As a young naval officer, he was respected by commoner mates, but he has said they never could understand why he did not resent his lack of freedom to join them at the local pub.

"Yes, I suppose I am conscious of being different," Charles once told an interviewer. "You don't know -- you can't know, can you? -- how much different. After all, you only know what it is to be you."

His social life is restricted largely to family gatherings at Buckingham Palace and various royal estates and to the private company of a few trustworthy, married, aristocratic couples of similar age. He has spent many solitary evenings in his three-room apartment in the palace. He enjoys serious music, once played the cello and has dabbled in watercolors. He plays polo, he has said, because his friends play it and it is the only game he is any good at. To appeal more to the average Briton, he has recently tried steeple-chase racing (and fell off his horse twice within one week).

He has acknowledged gravitating in his formative years toward older people, including his tutors, his parents, his grandmother and the late Lord Mountbatten, his favorite uncle and adviser on royal statemanship and behavior. He in turn was mentor to his considerably younger brothers, for whom he wrote years ago a long story about the fanciful adventures of a cave-dwelling Scotsman. "The Old Man of Lochnagar." It was published here last year as a children's book, with profits going to the Prince of Wales charities trust.

Prince Charles is reverently respectful of his family's role in the long tradition of the British monarchy. Unlike the "bicycle monarchs" elsewhere in northern Europe, British kings and queens retain, with public approval, considerable grandeur and ceremony. They also usually reign until death -- the most recent, and traumatic, exception being Charles' predecessor as Prince of Wales, who abdicated shortly after he became King Edward VIII. Though Charles has long had the same access as the queen to all secret government papers and frequently confers with government, business and labor leaders, he does not expect his mother to relinquish the throne so he can become king before he reaches late middle age.

Despite unwritten constitutional limitations on the crown and the modern tradition of avoiding public involvement in politics, the British monarch can still play an influential behind-the-scenes role. The prime minister meets privately with the queen once a wewek to exchange views and advice. The monarch also retains the power to decide after an election which potential prime minister to invite to form a government, power that could regain importance if a realignment of British politics, beginning with the birth earlier this year of the Centrist Social Democratic Party, makes a single-party majority in Parliament less likely.

With the throne comes a tax-free fortune estimated as high as $150 million, including a multitude of palaces, and estates and one of the world's greatest collections of art and artifacts, plus considerable help from the taxpayers toward the upkeep of the royal households, parks, vehicles and other items deemed beneficial to the public good and Britain's tourist trade. Prince Charles has had to be content with about $500,000 a year in income from the 100,000 acres of properties owned by the Duchy of Cornwall, half of which he voluntarily pays to the government in lieu of taxes. He may get some of this money back to meet the greater expenses of married life, which will include maintaining a nine-bedroom Georgian country house, Highgrove, in the Cotswold hills and a home in London yet to be chosen.

There has been persistent speculation, fueled by his visit to Australia, that Charles may become its crown-appointed governor-general after his marriage. The party currently in power in Australia favors it, but the opposition party is against it. There also is noisy anti-monarchist sentiment in Australia, recently manifest in demonstrations protesting the prince's visit.

But his wedding July 29 in St. Paul's Cathedral comes first. It will be the biggest event here since the queen's coronation in Westminster Abbey in 1952, and it is not likely to be equaled until the prince is crowned King Charles III and Lady Diana his queen. Prince Charles and his soon-to-be-princess are ensuring that the glittering ceremony will justify the expected large turnout of royalty and heads of state and a live worldwide television audience of an estimated two-thirds of a billion people. The wedding will show off one of the things that Britain still does best, and that's part of his job. Serious Business

Prince Charles does not like much that is written about him. He believes it creates the wrong impression by concentrating on what he regards as the photogenic trivia of his life: his social life before his engagement, his plans after marriage -- much of it gossip with little or no basis in truth. Lost in all this, he laments, are the serious things he is trying to say and accomplish, and for which he wants to be remembered during the decades of his adult life he will have spent as the Prince of Wales.

"I would like to be remembered," he told undergraduates a few years ago at Cambridge, where he had been the first Prince of Wales to earn a university degree, "for trying to show there is a way of motivating people, in trying to show that I have been concerned about their welfare and about their lives, about the things they feel strongly about or worry about. I would like to be remembered for taking a human interest in people in a world which tends to treat people like sheep or statistics."

He takes particular pride in writing his own speeches, usually after painstaking research at his desk in Buckingham Palace. They are dotted with referrences to British history, which he studied at Cambridge, and thinkers from Marx to Solzhenitsyn. They explore, for expert audiences, such subjects as education, engineering and advanced technology in Britain and include plentiful princely advice on how things might be done better. "Writing speeches is a major sweat," Charles said in a rare BBC radio interview on his 32nd birthday last Nov. 14. "Actually sitting down and thinking is a major sweat," he said, "and worrying about whether you are going to say the right thing is another problem, of course, because everyone will jump on you."

He made headlines and angered business leaders when he told industry executives in 1979 that they as well as labor unions were responsible for the "bloody-mindedness" in labor-management relations that contributed to Britain's economic decline. That and many other speeches have emphasized one of his favorite themes -- "the importance of the human factor" -- which he believes is too often ignored today.

In a recent newspaper essay advocating the "small is beautiful" message of E. F. Schumacher, Prince Charles urged that Third World countries such as India and declining industrial nations such as Britain develop labor-intensive, less depersonalized and energy-saving "intermediate technologies" as alternatives to the "rural, traditionaly existence" of the past and today's "urbanized, advanced technological environment."

He sees his role as using his influential position to help shape informed opinion on certain issues and possibly to prepare the British people for needed change. "Changing attitudes is, I have discovered, one of the most difficult things to achieve," he wrote recently. "The danger is that people may not stop and rethink where they are going until a disaster occurs."

He sees his worldwide travels, like his brief visit to the U.S., as important in helping to promote Britain and its exports and to attract foreign investment. He has said that "a bit of the hot air may have gone out of some of the more negative forms of Welsh nationalism" when he took an interest in Welsh affairs and language, braving nationalist demonstrations in the bargain, before and after his investiture as Prince of Wales at Caernarvon Castle in 1969.

In an effort to do something about what he sees as one of Britain's most important and potentially explosive problems, he devotes time to black and Asian Britons and organizations promoting racial harmony. He is not prejudiced himself, he has said, because he has traveled so widely "and seen many different peoples in their own environments, many of which I have admired and found fascinating."

This may sound superficial and naive. But Prince Charles has emphasized his belief that his unique upbringing has been matched by a unique opportunity to learn and impart his experience to others. "I don't exactly travel around this country, or other parts of the world, with my eyes tight shut or without listening to what experienced people has to say," he argued in a speech not long ago. "Consequently, I think it is sometimes possible for me to see things from a broader point of view and thus to pinpoint the sort of issues which need to be raised and discussed." Without Royal Regalia

Recently, Prince Charles arrived in New Cross, a largely black neighborhood in South London, without royal regalia. He was not astride a polo pony, at the controls of an aircraft or inside a diving suit descending into the sea. He was not dancing with or receiving a kiss from or being accompanied by any of the beautiful women who were so often part of the picture during his internationally celebrated bachelorhood.Lady Diana, already a glamorous celebrity who draws rapturous crowds, was nowhere in sight.

The prince's presence was not even the primary reason for the event, but it did ensure considerable media coverage of the opening of a new community center for the West Indian population of New Cross and a prayer service for 13 black youngsters who had died two months earlier in a house fire a few hundred yards away. That fire eventually put New Cross on the increasingly dotted map of race relations problems in Britain.

Charles had been to New Cross once before, in 1977, to visit what was then the community center in an old mission hall that later was also destroyed by fire. He had tried to cool down a confrontation with the police that his presence had attracted. He could remember, he said, "being very concerned that we should at all costs try to create something new here."

He contributed about $2,200 and the drawing power of his patronage to a building fund for the Pagnell Street Youth Community Center. Presenting the prince was a framed life membership, Trevor Sinclair, a West Indian-born member of the center's management committee, said, "We are extremely pleased at his visit and the interest he shows. He is very helpful."

Replicated hundreds of times a year, this is what the job of being the Prince of Wales is all about. He must stay out of politics, and he can make few command decisions other than designating the causes to which he will lend his name, patronage and person.

"I don't want to be a figurehead," he said a number of years ago upon assuming a full schedule of personal appearances and travel, plus long hours of meetings and paper work for a multitude of charitable and other organizations in which he is involved. "I want to help get things done."