Rep. Jon Hinson, a conservative Republican from central Mississippi, announced in his Jackson office yesterday that he was one of the survivors of the fatal 1977 fire at Cinema Follies, a Southeast Washington club that catered to homosexuals.

Hinson, who did not say he was a homosexual, also revealed that he had voluntarily filed a deposition on behalf of some of the relatives of nine persons killed in the fire. They have filed a $2 million civil damage suit aganst the club's owner.

Hinson also said he had been "accused" of committing an obscene act in Arlington in September 1976, and as a result had paid a $100 fine for creating a public nuisance. He did not say what the act was, however, and Arlington police and the county's District Court had no record of Hinson's arrest or fine.

Reporters at the hastily called news conference looked on with growing amazement yesterday morning as the 36-year-old freshman congressman read a five-page statement that began, "There are few who find it easy to engage in public discussion of that within us which strips bare our human frailty."

Then, after discussion of a 12-month period in 1976 and 1977 when I was visited with every fear and self-doubt ever conceived," Hinson said he had been present at the Cinema Follies fire and had paid the fine for the Arlington offense.

"I must be totally frank and tell you that both of these incidents were in areas frequented by some of Washington's homosexual community," he added.

Near the close of his statement, Hinson said that for himself and his wife Cynthia, "this press conference offers . . . some relief and I think you will understand that we find comfort in being able in a complete sense to put these incidents behind us -- finally."

Hinson left the press conference immediately after finishing his statement, taking no questions from reporters. He could not be reached later yesterday afternoon.

"He has no further comment to make at this time," said his Washington press secretary, Rebecca Schneider.

The unexpected statement by Hinson, a former Marine and congressional aide who succeeded Thad Cochran, now a U.S. senator, as Mississippi's Fourth District congressman, bewildered the state's political community.

Hinson was expected to be reelected easily. A longtime Ronald Reagan supporter in a conservative district, he won election by a margin of 26 percentage points in 1978, and this year he was facing a Democrat and a black independent who were expected to split the moderate and liberal votes.

"He was very far ahead in the numbers," said Mississippi's Republican state chairman Michael Retzer.

But in nearly two years on Capitol Hill, Retzer said, Hinson has been "frank to a fault." And, the state chairman added, Hinson tends to bare his soul about unpopular political stands, drawing more attention to them than they would otherwise receive.

"He voted against making Martin Luther King's birthday a national holiday, then issued a press release to explain why," said Retzer. About 40 percent of the voters in Hinson's district are black, Retzer said.

But the reasons for this disclosure were even less clear to Retzer and other political leaders around the state. Friends and political allies who discussed the situation with the congressman the past few months had urged him to keep silent about it.

"When Jon asked me what he should do months ago I told him not to disclose this," said W.E. (Gene) Simmons, one of Hinson's oldest friends and the owner of a lumber yard in Tylertown, the small (pop. 2,000) dairy farming community where Hinson grew up.

"It's not like misconduct in office," Simmons added. "He just got caught in a one in a million fire. It could happen to anyone."

Simmons added that "the obvious implications -- that Jon is gay -- are false . . . That doesn't change his ability to do his job, but if that label gets hung on him, it would hurt him here."

Wirt Yerger Jr., once chairman of the state Republican party, had a different view. "I think -- well, it's too early to tell -- but when people look at the large picture, and the philosophy he represents, and his being the only conservatie in the race in a conservative district, and the fact he's put his life back together and is happily married, I'm not sure how much difference it will make.

"I'm not saying it is an asset -- don't misunderstand me," Yerger added. " . . . But I think there's an excellent chance of his being reelected. Thomas Eagleton's still in the U.S. Senate and my goodness he's had shock treatment and everything else."

Other political observers were more dubious. "This changes everything." said one.

Hinson's Democratic opponent, Jackson attorney Britt Singletary, refused to talk to reporters after the press conference yesterday.

But others in Mississippi's Republican political circles indicated that rumors about Hinson had begun to circulate which, along with his desire to make public the two incidents, prompted yesterday's statement.

"There were a lot of rumors flying around and rather than have a lot of misinformation around, they decided they would come out with this," said Retzer.

"The whole business of repentance involves confession, and maybe with public officials it involves public confession," Retzer added. "Though most of us prefer to confess in private."

"I don't think this is going to hurt him one bit," said Clifton Hinson, the congressman's father, who was informed of the incidents by his son Thursday night. "Everybody's probably got a little skeleton in his closet."

The Cinema Follies fire broke out at 5 p.m. on Oct. 24, 1977, when a spark from a rug shampooer ignited cleaning fluid in the carpet on the first story of the building and flames rushed upstairs to the second floor, where about 13 men were watching X-rated movies. The fire blocked the only exit.

All four men rescued were helped out a second-floor window by firemen who had fought through the flames. Hinson, who was an aide to then-representative Cochran, was slightly injured, he said yesterday.