Christina Onassis, who inherited one of the great private fortunes in the West, married a $120-a-week Soviet shipping official here yesterday to seek a simple life as Mrs. Sergei Kauzov, resident of Moscow.

The 27-year-old Greek bride, stepdaughter of Jacqueline Kennedy Onassis, arrived at the wedding in a beat-up Chevrolet Nova belonging to a Greek diplomat. She wore a long mauve gown with purple flowers.

She left the "Palace of Weddings" 32 minutes later on the hand of her 37-year-old Russian husband and clutching a bouquet of red and white roses.

Ignoring scores of photographers and reporters, the newlyweds drove off in a Soviet-made Volga with Kauzov at the wheel. Onassis, obviously nervous, almost tripped as she emerged into the beautiful summer morning. Kauzov in a smartly tailored dark pin-striped suit, had some difficulty starting the Volga.

As if to add another fairy-tale quality to the event, which without precedent in 60 years of Soviet rule, the couple will spend their honeymoon in Siberia on the shores of Lake Baikal. Then they plan to join Kauzov's mother in her two-room Moscow apartment, which is to serve as their temporary home.

Kauzov, who is a member of the Communist Party, divorced his wife of 10 years recently to marry Onassis. He has asserted that he is not interested in the $500 million in shipping and real estate enterprises she inherited from her father, Aristotle Onassis.

The new Mrs. Kauzov, who is the major shareholder of the Onassis interests, has said that their control will remain in the hands of her father's trusted associates in Western Europe.

She told her new friends here that she wants tosettle to a simple life. Despite "so much luxury in my life," she said she was through with the jet set.

"Everybody knows that until now I have not had much happiness in my life," she was quoted saying. "I want to be left alone. I won't have any problems in adjusting to a simple life."

But the marriage has raised a number of complex questions about the future ownership of the Onassis interests. Should the couple have a child in the Soviet Union, he or she would automatically be regarded here as a Soviet citizen entitled to inherit the fortune.

There is no way of knowing how Onassis and her lawyers might deal with such a situation.

Also under Soviet law, it is common practice that in divorce cases, where there is no prior mutual agreement on property questions, courts usually divide holdings on a 50-50 basis. It is believed that Onassis took legal steps to protect her property rights, but no information on the subject was available.

The wedding was the first on the list of those scheduled yesterday at the Palace of Weddings housed in a neoclassical one-story mansion on Griboyedov Street in central Moscow.

In a simple ceremony, the daughter of a man who was once viewed here as a symbol of evil in the capitalist world pledged that she would do her duties as the wife of a Soviet citizen.

The registrar, Klara Lemeshkova, who wished the couple happiness and success in their new life, also cautioned the groom: "Wherever you live, do not forget you Soviet motherland."

The pair exchanged rings, kissed, and signed the marriage documents. Only eight guests and three Soviet photographers were allowed to attend.

Among the guests were Kauzov's mother, Mariya Sergeyevna, Soviet film director Yuli Reisman, for whom Mariya Sergeyevna works as an assistant, and Ursula Kalogeras, wife of the Greek ambassador. The ambassador was absent, according to Greek sources, because Greece's official Orthodox church does not recognize civil marriages.

John Fotopoulos, first secretary in the Green Embassy, and an unidentified friend of Kauzov's served as witnesses. Apparently no Onassis relatives were present.

The newlyweds were then toasted with champagne inside the orante, wood-paneled room with elaborate chandeliers. A string emsemble was deployed to play Mendelssohn's wedding march, an optional extra for couples who do not want to settle for a taped version.

The ceremony, which cost 1 1/2 rubles, or the equivalent of a little over $2, ended with a recording of bells.

Since Onassis was determined to sun the Western press, Moscow provided an ideal setting for secrecy. A police major guarding the entrance to the mansion read the names of the 11 invited guests, then ordered the crowd to stay on the opposite side of the street. Onassis' romance and marriage to Kauzov have not yet been reported by the Soviet media.

Scores of reporters, cameramen and photographers who gathered in the otherwise quiet street provided a major event in the neighborhood.

Women in white and red scarves who were working on the large construction site next to the palace joined the crowd. Old ladies in surrounding buildings leaned out of their windows.

The wedding lasted longer than normal. Half way through it, a large black Chaika sedan decorated with pink ribbons deposited the next couple to be married along with well wishers and relatives carrying balloons. The bride, dressed in white, seemed surprised by the large crowd of photographers and cameramen, and the groom blinked in amazement. Another wedding party showed up a few minutes later but - they were directed by the police to circle the block.

When the Kauzovs emerged from the building, a crowd of reporters and photographers pressed around them. They entered Kauzov's Volga with some diifficulty.Its windshield wipers were removed in case someone might try to steal them, as is the case with most Soviet cars.

"I feel fine, very good," was the only thing the bride said. Kauzov, only smiled nervously.

There was to have been a news conference yesterday afternoon, but family spokesmen hurriedly called journalists to inform them that Mrs. Kauzov did not feel like talking to the press. The cancellation left many questions and conflicting rumours in the air.

Onassis spent a month before her marriage living in a suite in the Intourist Hotel here, and dismissing all rumors about the marriage to a Soviet offical as "preposterous". Last week, she finall admitted that she would marry Kauzov.

Kauzov is a graduate of Moscow's Institute of Foreign Languages. He is fluent in English and also speaks French. His father was killed in the Leningrad front in 1942, and he is said to be devoted to his mother.

After graduation, he served with the state shipping firm, Sovfracht, and he met Onassis first when she came here in 1976 to negotiate a business deal with Sovfracht.

He was subsequently sent to Sovfracht's office in Paris where their romance blossomed. Two months ago he quietly divorced his wife Nataliya. The court awarded the custody of their nine-year-old daughter Katya to the mother.

Despite having lost an eye in a childhood accident, Kauzov is a handsome man with an intelligent pale face and thinning sandy hair. When asked last week why a loyal Communist would marry one of the richest women in the world he said, "It doesn't make any difference whether you are a capitalist or a Communist if you happen to be in love with each other."

Some reports said that Kauzov was granted an extended leave of absence from Sovfracht. Others allege that he had quit the agency altogether. There were also reports that he would join an office representing Onassis' interests which his wife intends to open in Moscow, be he firmly denied that.

Greek sources said that Onassis' friends had advised her against the marriage, arguing that she was being naive about her prospective life here compared to her past.

Except for her visit to the Kauzov's apartment, which was redecorated to impress the new family member, and frequent outings to restaurants, she has seen very little of Soviet life.

But she is known as a strong-willed person who defied her father in 1971 when she married Joseph Bolker, a Los Angeles real estate broker, who was almost twice her age.