The first American film festival in China in several decades has been delayed six months because of Chinese resistance to several films, including "Breaking Away," "Singing in the Rain," and "Shane."

"Perhaps the Chinese were bothered that Shane was not operating in accordance with a central directive," an American diplomat suggested in jest after "Shane," the classic tale of a lone cowboy, was picked last by the Chinese to round out the number of films to five.

Sources here said the Chinese first would accept only "The Black Stallion" and "Snow White and the Seven Dwarves" from a suggested list of 10 films and asked to see others. When U.S. negotiators refused to provide more, the Chinese Culture Ministry officials agreed to take "Guess Who's Coming to Dinner," but only after it was pointed out that a Chinese theatrical company had done the same story on stage in Peking. After four months of further talks, they finally accepted "Singing in the Rain" and "Shane."

The Chinese gave no clear reason for their choices other than that they thought some of the films "inappropriate."

"If you try to figure out why the Chinese pick and choose, you go mad," said one observer.

The Chinese rejected "Breaking Away," "East of Eden," "Patton," "To Kill a Mockingbird" and "Raisin in the Sun." They asked for "The Sound of Music" and "Norma Rae," but balked at the asking prices. Only a few, usually second-rate, American films have been shown here, because the Chinese authorities have refused to pay more than a flat fee of $10,000 for rights to show any foreign film in China. Major American film distributors, who agreed to provide some films on a special basis for the government-run film festival, are insisting on a percentage of theater receipts for regular commercial showings as they do in other foreign countries.

As the Chinese continued to insist that the films offered were "inappropriate," one member of the American side complained about some of the few U.S. films the Chinese had bought and shown widely, including "Convoy" and "Nightmare in Badham County." The latter film, the story of two female college students brutalized on an American prison farm, was widely shown throughout China a month ago.

"Those films distort American life," an offical objected. The Chinese replied that they understood that now, and had reduced the number of showings.

Officials were at a loss to explain the rejection of "Patton," which has been shown to enthusiastic private audiences here for years. "Every Chinese I know has seen 'Patton,' one American said.

Other foreign embassies here have reported resistance and uncertainty on the part of the Chinese when faced with the chore of deciding what Western films to show. "They want modernization without westernization," said one diplomat.

The agreement to exchange films between the United States and China was signed during Vice President Mondale's August 1979 visit to China. The festivals here and in the United States were to occur this fall, but now will be delayed at least until spring of 1981. The U.S. International Communications Agency will provide Chinese subtitles for the films.

The Chinese have sent 10 films to the United States to be reviewed by the American Film Institute, one possible sponsor for the American Festival. The films include a colorful cartoon appreciated by American children who have see it here, "Nezhoa Conquers the dragon King," and the big hit of China's 1979 film season, "Little Flower," the story of a young girl separated from her family during war.

The U.S. films will be show in Peking, Shanghai, Tianjin, Xian and Wuhan. An American official said the films would be shown only for a week "and I expect the Chinese will tear the doors off the theaters to get in."