A federal jury in Alexandria convicted retired CIA analyst Larry Wu-Tai Chin of espionage yesterday in the sale of classified information to Chinese intelligence agents for more than 30 years.

The jury, which deliberated a little more than three hours, also found the 63-year-old Chin guilty of conspiracy, filing false income tax returns and failing to report foreign bank accounts.

A tall, thin man who displayed a meek demeanor throughout his four-day trial, Chin showed no emotion as the verdict was delivered. His wife Cathy, sitting behind him in the gallery, broke into sobs. As he was led from the courtroom, Chin paused by the door and gave her a long look.

Chin testified during the trial that he had passed classified information to the Chinese as part of a personal "mission" to reconcile differences between China and the United States. He said that more than $180,000 he received from Chinese intelligence agents was "only a byproduct" of that mission.

U.S. District Judge Robert R. Merhige Jr. said he would set a date for Chin's sentencing next week. Chin faces up to two life sentences, plus 83 additional years in prison, as well as $3.3 million in fines for his conviction on all 17 counts on which he had been indicted.

"We are obviously pleased by the verdict, which was supported by the evidence," said Assistant U.S. Attorney Joseph J. Aronica, the lead prosecutor. "It's sad to discover an American citizen has been spying for another country for 30 years."

Chin's attorney, Jacob A. Stein, said he would appeal the verdict. He said the jury should have been instructed that the absence from the trial of a key government informant might be taken as favorable evidence for his client.

The informant's identity was not disclosed by prosecutors, but Chin has speculated that the government's knowledge of his activities could only have come from a Chinese intelligence agent named Ou Qiming and that Ou had defected.

Chin testified on Thursday that he met Ou over a period of several years and passed him classified documents. A government exhibit at the trial identified Ou as "deputy chief, first division, second bureau, Guangdong Provincial Security Bureau."

The government blocked any testimony that would have elaborated on Ou's role in the case.

Yesterday's verdict ended what is believed to be the first trial involving a longtime foreign spy operating inside the CIA.

Chin, born in Peking and later naturalized as an American, began his work for the United States as a secretary-interpreter at the U.S. Consulate in Shanghai in l949. He then worked for the U.S. Consulate in Hong Kong and in l952 helped the State Department interrogate Chinese prisoners captured in the Korean War.

He began his CIA career when he joined the agency's Foreign Broadcast Information Service in Okinawa. FBIS employes monitor and translate foreign radio broadcasts and publications for the CIA. He later worked for FBIS in Santa Rosa, Calif., and transferred to the service's Rosslyn office in 1970. He worked there until his retirement in l981, earning a reputation as one of the office's best Chinese analysts.

The jury found that Chin passed secret information from his POW interrogations to Communist Chinese agents in the early 1950s. After gaining a security clearance in 1970, Chin also passed classified documents to the Chinese until his retirement, the jurors determined.

According to prosecution evidence, Chin had access to hundreds of classified documents, including handwritten notes from covert agents and intelligence reports presented to the White House.

Prosecutors Aronica and Kent Robinson presented entries from Chin's own meticulously kept diaries that detailed his meetings with Ou in Hong Kong, with a Chinese contact in Toronto and with senior intelligence officials in Peking during a l982 trip there.

In his closing argument yesterday, Aronica called Chin "a mole" in the CIA. "Those documents, which were being read by the CIA, the National Security Agency, the Joint Chiefs of Staff, the president -- those same documents are arriving in Peking and being read by members of the Chinese Politburo. Incredible!" Aronica said.

Stein, in his summation, said the government had failed to produce "the dead body," a reference to the inability of prosecutors to identify any specific document Chin gave the Chinese, except for one that Chin admitted handing them in l970. That was a then-secret report on President Nixon's intentions to normalize relations with China.

Stein offered no defense to the income tax and financial reporting charges, saying his client admitted those offenses. But he asked the jury to acquit Chin of espionage, citing Chin's testimony Thursday that he had passed the classified information only to help reconcile China and the United States.

Chin testified that he had embarked on a private "mission" to overcome Chinese paranoia by passing information that showed Washington's desires for normal relations. He said the money he received in return was "only a byproduct" of the mission. He denied ever passing any U.S. military or weapons secrets.

Prosecutors presented evidence showing that Chin had received more than $180,000 from the Chinese and had invested some of it in about 30 rental properties.