It has all the trappings of a mini-CIA operation or a James Bond movie.

There are code names, unmarked offices where people work behind locked doors, secret couriers between New York and Chicago, decoys working on dummy projects to throw snoopers off the trail. At times people involved in the project don't even know that they are.

Spooky as it might sound, it is just part of how the Man of the Year gets on the cover of Time magazine. It also helps Time both keep the identity of its annual selection secret while spurring speculation about the choice.

"We're pretty amateurish about it." Time executive editor Edward L. Jameson said, "but then the CIA is sometimes, too."

The 1977 Man of the Year will be announced this weekend. The oddson favorite is Egyptian President Anwar Sadat. And there is speculation that Sadat may share the honors with Israeli Prime Minister Menahan Begin. But, then, who know? In the half-century since Time has been choosing the Man of the Year, its editors have come up with plenty of surprises.

This year is the 50th anniversary of the Man of the Year, although the designee will be the 51st. And over the years the selection has caused anger, controversy and suspense. In fact, it has become a news event in itself.

Last week, for instance, reporters covering the Cairo peace talks spotted Sadat posing in the shadow of the Sphinx and the Pyramids. Pictures were being taken from helicopters. Aides of the president said that Sadat had been chosen Man of the Year and would be the subject of Time's cover story. That piece of information ran on news services and the network newscasts.

Time executives, as would be expected, remained silent.

Time officials won't tell outsiders who is working on this year's cover story, where the project is being completed or what its code name is. The artwork for the cover will be carried by a messenger to the Chicago printer. The cover artwork is normally sent by air freight.

What has become a national tradition began almost by accident. When the editors of the 5-year-old magazine were putting out the first edition for 1928, they realized that the previous week's news - the last week of 1927 - had been very dull. No one had done anything newsworthy enough to qualify for Time's cover. Someone suggested that the magazine instead pick a Man of the Year.

The designation went to Charles A. Lindergh. He was selected to appear on the cover of the issue for the last week of 1927, dated Jan. 3, 1928, for his solo flight across the Atlantic.

The success of the first man of the Year caught the Time editors by surprise, and they made it an annual event. But they insisted from the start that the choice was not to be an accolade or an endorsement. It was not to be considered by anybody to be the equivalent of a Nobel Prize. Nor was it a moral judgment. (Al Capone came close to being the Man of the Year of 1928.)

From the outset and throughout its history, the Man of the Year has been selected on the basis of three criteria: Who had the biggest rise in fame, who dominated the news that year, who left an indelible mark - for good or ill - on history.

Since Lindbergy, Man of the Year selctions have been as varied as the world itself, Franklin Delano Roosevelt was Man of the Year three times - more than any other individual. Selected twice were Soviet dictator Josef Stalin, Presidents Dwight D. Eisenhower and Harry S. Truman, and Gen. George C. Marshall. Winston Churchill was selected Man of the Year in 1940 and Man of Half Century in 1949 when there was no Man of the Year. Richard M. Nixon was Man of the Year once and shared the cover with Henry A. Kissinger another time.

Despite the speculation each year about the Man of the Year, the editors maintain that they are able to make changes until the pages are locked up and the printing presses roll. This year that is expected to happen late Saturday.

The process of section begins usually in early fall when the editors in New York ask correspondents throughout the world for their nominations.

In early December the field is narrowed to fewer than a dozen. Although thousands of letters come in from the public, the final decision is up to the managing editor. (this year's mail votes range from Anita Bryant to Billy Carter, with Sadat far out front.) Even Henry R. Luce, confounder of the Time, Inc., empire, has had no say over the managing editor's selection.

The tale probably is aprocryphal, but one year a leading gossip columnist thought he knew who Time had chosen for Man of the Year. According to the story, Walter Winchell flashed the word it would be "a Chinese general named Moy."

He obviously had the inside word. "MOY" is Time's in-house nickname for the annual project.