It isn't a big exhibit and it hasn't been seen by hordes of art loves, but its own way, a modest show by the Museum of Oriental Art here provides a glimpse at a fascinating, elusive Russian subject: Soviet officialdom's ginerly approach to the abstract art of its own dazzling - and suppressed - 20th-century painters. The small show, exhibiting less than 100 works, also shows that those painters themselves were preoccupied with in the early years of this century, when violent revolution was about to transform the world they knew.

The show is called "Russian Art On the Brink of the 19th and 20th Century," giving no hint that inside one can find works by Alexander Volkov, Natalia Goncharova, pavel Filonov, and other seldom-seen painters of expressionism, abstract expressionism cubism and later pioneering trends in modern art.

The official commentary for the show declares that the period 1880-1910 "was the most interesting and complicated period of Russian art . . . new forms appear in art, new values needing a new artistic language." The text says that many artists of the time "turned to Oriental art motifs, which appeared in the work of many artists then."

In an effort to eplicate this theme, the show's curators have displayed paintings and objects d'art from ancient Central Asian artisans adjacent to the modern works. The effect is interesting, but most of the people present to be drinking in the modernists.

"This is what I came for," said one young woman, staring intently at a Lentulov canvas entitled "Kiolovodsk," a serene composition of impressionistic planes of quiet color, suggesting the Russian resort town on a summer day.

But another viewer winked at a Westerner slyly. "I wonder what they have in the basement? I guess it's a better collection down there."

For an officialdom that prefers the heroic optimism of Socialist realism, the appearance of a painting such as Alexander Volkov's "Caravan in the Desert" seems slightly out of place, This large oil and tempura on canvas shows somber reds, tans and black huges worked into brooding triangles and circles. It was painted in 1922, well out of the period of the exhibit, and is far from realistic. One person remarked that the exhibit title was simply a means to get some non-conformist works on the halls.

Other paintings by these modernists range from grim-faced figures by Filonov to peaceful, rich still lifes by Kuprin, Mashkov and others, and a striking oil and collage by Lentulov entitled, "Portrait with Birch Tree in the Background," showing in strong, bitter strokes a seated woman with a sharp, powerful face staring challengingly at the viewer.

Many of the works displayed here are tame by the standards of such painters as Kandinsky, Chagall, or Malevich, artists long known in the West for their experimental work. But only in recent years have the Soviets occasionally been able to find space on the walls of their official galleries for these painters. The gradual embrace of avant-garde art has been pushed along this year by George Costakis, a Moscow-born Greek whose extraordinary collection of modern Russian art has been sent by the rich and powerful visiting here from around the world. Their praise has led to small loan abroad of selected paintings in his collection, and the resultant praise has not gone unnoticed in official circles, it is believed. Coastakis has decided to leave most of his nearly priceless collection here when he retires soon and leaves Russia. In return, he has said he believes he has an official promise that the works will be publicly displayed in a timely fashion.

There has for many years existed an "unofficial" art world here displaying the works of painters and sculptors who toil by day on officially approved projects and spend their nights venting deeper, creative impulse s on private works which can become available to potential buyers from the West.

Only members of an official trade union can sell their paintings legally. A number of present "official" artists not so long ago were on the wrong side of the conservative bueaucracy. In 1974, police and civilian militia with bulldozers and water cannons broke up an unofficial outdoor art show and beat up a number of people there. But that act of repression, widely reported in the West, seemed to spawn a blacklash, and within time, some of the same artists' works were hung in an officially sanctioned show. Now, a number of the original participants are officially recognized and mingle at selected foreign embassy parties along with other official government figures.

Some artists have remained outside the official embrace. One of these, Oskar Rabin, a leading non-conformist artist who helped organize the 1974 outdoor show that was broken last week he must find official work or face a charge of "parasitism," which could mean a jail sentence. In addition, the government has apparently broken up a non-conformist art team by allowing one member to emigrate to Israel while denying permission to the other. Alik Melamid has been told he can leave, but Vitali Komar has been refused. The two men, expelled from the artists' union in 1972, have created an art form they call "sotsart ," (socialist art), a quasi-satirical version of Socialist Realism. Some of their work has been exhibited in the West.