Last February, Stanley Lubman found himself in Peking explaining Ground Hog Day to a group of Chinese trade negotiators.

The significance of the ground hog's shadow wasn't a problem. "But there was a certain difficulty translating what a ground hog was," said Lubman recently. "We decided in the end that people in both countries ate ground hogs. That's something I didn't know."

Since 1972, Lubman has been interpreting business, law and, occasionally, culture to participants in trade between the U.S. and the People's Republic of China.

This April, Lubman assisted in the first American sale of an oil rig to China. The mobile jack-up drilling platform was sold by Bethlehem Singapore, an affiliate of Bethlehem Steel Corp.

At the request of the Chinese, Lubman declined to give specifics of the rig or say where it will be used. But the Far Eastern Economic Review reported that the rig's ability to operate in up to 250 feet of water while resting on soft seabeds makes it suitable for exploration in the South China Sea off Kwangtung Province.

Lubman recently returned from his 15th trip to China. He is one of the handful of American lawyers trained in Chinese law and language, and one of the very few China trade specialist in the U.S.

Lubman was selected by the Rockefeller Foundation in 1963 for Chinese legal training at Columbia Law School. At that time, "The foundation decided that some day the U.S. and China might communicate with each other again," Lubman said. "There were no American lawyers or law professors then doing any research at all on China."

Lubman began teaching Chinese law at the University of California at Berkeley in 1967. In what turned out to be a prescient move, he used his nonteaching time to interview foreign participants in and observers of China trade.

The U.S. did not trade with China until after President Nixon's visit in 1972. But Europeans were trading with China all along, as were businesses based in Canada, Japan, Hong Kong, and other countries. These traders provided Lubman with important but, at that time, unusable details on Chinese markets, access to China, types of contracts, and contractual disputes.

Nixon's unexpected China visit and the reopening of U.S.-China trade changed all that. Suddenly Lubman's knowledge and research were not only usable but something a hot item. So Luman opened a law office in San Francisco to advise would-be American China traders. His wife Judith founded Lubman and Co. agent for importers of Chinese goods.

The Lubmans moved to Washington in 1974 but returned to San Francisco in 1976 when Lubman found he needed the support of a larger organization and wanted to expand his practice to include trade with Southeast Asia. He joined the law firm of Heller, Ehrman, White and McAuliffe.

The use of lawyers in China trade is an American phenomenon. Other countries rarely was attorneys in commercial transactions.As a result, Lubman has taken quite a bit of teasing from Chinese counterparts about his profession.

"In traditional Chineser belief, there was the idea that proper ways of behavior should come from within and not from rules imposed from above," explained Lubman. "There was no class of lawyers. There were people who assisted litigants before the magistrates who were known as litigation tricksters - which illustrates traditional Chinese attitudes towards lawyers, some of which continue to exist today."

But Lubman said the negotiator "who teased me, saying 'we don't need lawyers, lawyers have never been very important in the trade,' was every bit as picky about nuances in contract clauses as any lawyer."

"The Chinese are very careful shoppers," said Lubman. "They want to know a great deal about the machinery and equipment that's included, how it works, safety factors, back-up systems . . ."

As is true in many Chinese purchases of foreign technology, all the training necessary for the Chinese to operate the drilling rig will take place outside of China. When the rig is completed in early 1979, the Chinese simply will tow it away.

Competition among American drilling rig builders for sales in China, seen by experts as one of the few vast untapped sources of petroleum remaining, has been lively. Delegations of Chinese petroleum equipment specialist have toured the U.S. to observe American technology, and American engineers have held technical seminars in China. Bethlehem Singapore had a leg up on the competition because its rig was under construction at the time of the Chinese sale.

Another advantage was Singapore's proximity to China. Not only could the rig be delivered sooner than one constructed in Texas, for example, but the cost of towing to China would be considerably less. Much of the drilling equipment manufactured in Singapore by a variety of companies is destined for Chinese use.

Negotiations in China are often grueling, but the Chinese are solicitous hosts. The Bethleham team was treated to visits to the Great Wall, the Ming tombs, the site of the discovery of the Peking Man, and Mao Tse-tung's mausoleum, as well as a number of banquets.

Lubman's role in the Bethlehem rig sale began when he discussed the transaction with Chinese trade officials while there on other business. He oversaw the ensuing correspondence and then accompanied Bethlehem representatives to China for three weeks of technical discussions.

Lubman's fluency in Mandarin Chinese ingratiated him with his hosts and allowed him to monitor the work of the interpreters to clear up misunderstandings.

"One of the Chinese team members had been a student of foreign literature," recalled Lubman. "I asked if he had had time to read any lately. He replied, "No, I've been too busy the last 20 years reading contract clauses'."

"Sounds like some lawyers I know," laughed Lubman.