Harry Roe Hughes was sworn in today for a second term as Maryland's 57th governor, promising that unlike the Republican government in Washington, his administration will not turn its back on the poor, the needy, the unemployed.

"In Washington, the administration insists that jobs will come if only we wait it out," declared Democrat Hughes in a 20-minute inaugural address. "In Maryland we say jobs will come only if we refuse to wait it out. In Washington, the administration has insisted that the defense budget was untouchable and that raising the level of human services was unthinkable. In Maryland we say to degrade human service is unthinkable . . .

"It is no coincidence to me that many who preach the theory of supply-side economics seem to be those who can afford standing comfortable on the side where the supply is, while 12 million out-of-work Americans are left to languish where the supply isn't," he said.

Throughout his speech, delivered on the steps of the State Capitol to a crowd of 500 to 600 shivering state officials and supporters, Hughes, 56, focused harshly on the Reagan administration, comparing it unfavorably to the Democratic government and policies of Maryland.

Only at the end did he return briefly to the topic that brought him to the State House against all odds four years ago--integrity in government. "I said [in the 1979 inaugural address] that integrity and independence would be the hallmark of the new administration . . . I would not have changed a word of it then, and I find no cause to change a word of it now," the governor said.

The fleeting mention of honesty in government was but one of the many constrasts between Hughes' first inauguration and the ceremony today. Four years ago, Hughes was sworn in on a snowy, overcast day after upsetting the state's political establishment. Today, when Hughes took the oath of office on a freezing but sunny day, he was the political establishment, an incumbent easily reelected with the support of nearly every elected official in Maryland.

Standing with Hughes today was a new lieutenant governor, J. Joseph Curran Jr., a close friend and former Baltimore state senator with significantly more State House experience than the man Hughes ran with in 1979 and then dumped last year--Samuel Bogley.

The inauguration began just before noon when Hughes and Curran, in morning coats, accompanied by their wives, were escorted from Government House, the governor's official residence, to the State House just across the street by a procession of formally clad legislative leaders, red-robed judges and uniformed National Guard members.

In the ornate state Senate chamber and gallery, which was filled with 225 dignitaries, friends and family members, Curran and then Hughes were sworn in by Robert C. Murphy, chief judge of the Maryland Court of Appeals.

Just before he officially became the state's third lieutenant governor of recent times, the beaming Curran looked up to the gallery and waved to his brothers, Mike, a Baltimore City Council member, and Robert. Hughes took the oath on a Bible that had been used in his mother's family for several generations.

Among those who witnessed the swearing in were a host of state and national figures, Democrats all, including U.S. Sen. Paul S. Sarbanes, Maryland Attorney General Stephen H. Sachs, U.S. Rep. Steny H. Hoyer, and former U.S. secretary of Defense Clark Clifford, whom Hughes had selected to deliver the introductory address for him this year and at his inauguration in 1979.

Because the Senate has such a small chamber, dozens of other guests watched the ceremony on television sets strategically placed throughout the historic State House. Maryland's public television network broadcast the inauguration live.

After the swearing in, Hughes, Curran and the procession of legislators and other dignitaries moved outdoors, to the west side of the State House, where a huge speakers' platform was protected from the harsh cold by a clear plastic covering and warmed by kerosene heaters.

Below the platform, the United States Naval Academy Band played the Star Spangled Banner and state officials, legislators and their spouses, and other guests huddled in groups for warmth.

In introducing Hughes, Clifford noted "what remarkable changes the four years [under the Hughes administration] have brought." Likening Maryland's governor to president Harry S. Truman, whom Hughes admires, Clifford said, "I have known two outstanding Harrys in my life. The first is Harry Truman. The other is Harry Hughes. Both are modest men who grew and developed in office. Both are honest men with a record of personal integrity and they both have demonstrated rare courage."

Clifford praised Hughes for being willing "to reject the disastrous policies issuing from Washington at this time."

Hughes then picked up that theme in his remarks, which he read without deviation as prepared for him by his media consultant and friend, Robert Goodman, and his press aide, Lou Panos. Interrupted only twice by polite applause from the sparse, chilled crowd, Hughes castigated the Reagan administration without mentioning it by name, and pointed to Maryland as an example of a compassionate government.

Hughes read from a letter sent to him by Clara P. Denton, a 90-year-old Cambridge woman, who thanked him for the state program that helped her move out of a nursing home and into the home of a friend.

And then, to end his address, Hughes quoted from a speech given 174 years ago by Thomas Jefferson, saying: "The care of human life and happiness, and not their destruction, is the first and only legitimate object of good government."