Isaac Stern learned at least two words of Chinese during his two-week visit to China, and he used them both last night at the Chinese Embassy. "How-gi-la," said Stern, replying to a toast by Ambassador Chai Zemin and explaining that it meant "wonderful, marvelous or magical." Then he added "lieo-bo-chi," which means "great."

Either word might be applied to the embassy party, whose guest list included a glittering array of performing artists who have toured in China: not only Stern but conductor Eugene Ormandy, soprano Roberta Peters and pianist Gita Karasik. Also present was Martha Graham, who has been invited to China but is still discussing details. "The only thing holding us back is money," Graham explained. "I donht want to go alone, just as a lecturer -- a talker. I want to bring my company and show what we do."

The evening was highlighted by excerpts from a film, "From Mao to Mozart: Isaac Stern in China," which was produced by the Harmony Film Group and has been nominated for an Academy Award as best documentary. It shows Stern briefly in concert and at length holding master classes with young Chinese violinists. "Music is not black and white," Stern explains to a teen-age girl playing Beethoven's "Spring" sonata, "it has all the colors, including some that even painters do not have." He asks another to sing a passage and then imitate her singing on the violin. He tells a whole audience that "the violin must be a part of the body -- like another arm," shows how it is gripped between shoulder and chin, then explains that "I have a secret," pulling out a large foam-rubber pad that he keeps under his shirt to protect his shoulder. Even before an interpreter can put his words into Chinese, he establishes a simple, direct communication with his listeners.

"I couldn't handle Chinese," Stern said after the film, as the guests were heading upstairs for a buffet dinner of steamed dumplings, beancakes, noodles and various chicken, pork and fish dishes, "but I was able to communicate with quite a few people in Russian." He also had trouble with the er hu, a Chinese instrument that is the country's closest equivalent to the violin. "I tried the bloody thing," he said, "but it's very hard. But I heard one kid who was marvelous on it; she played Chinese and Western music and she could really make that instrument sing."

As performers return from Chinese tours, word is beginning to spread in American musical circles about some remarkable talent in China. Gita Karasik, who gave both concerts and master classes on her tour, said the talent in China is "so remarkable, and they're so receptive." Stern thinks that the Chinese may have a specially sensitive ear for music because their language is "full of tonal inflections -- very subtle." The ambassador wasn't so sure. "I would be lost at a concert," he told his guests through an interpreter.

Stern's siter, Eva Hornyak, was deep in conversation with Rep. Sidney Yates (D-Ill.). "Can you save our program?" she asked the congressman, who had been introduced as a friend of arts programs. She explained that her program, the University Community Concerts on the College Park campus of the University of Maryland, gets "about one-third of our money from the National Endowment for the Arts.

"What Reagan doesn't understand," she said, "is that this money generates so much more from the audiences -- it's a kind of a seal of quality."

Yates looked helpless and slightly unhappy. "What a savior everyone wants me to be," he said