After four years of being about as fashionable as a hula hoop, that bastion of Republicanism called The Capitol Hill Club is back in style. So is Anna Chennault.

Last night it was Chennault's turn to preside there at festivities marking the GOP's return to the mainstream of political wheeling and dealing. She co-hosted a reception for new GOP senators given by the National Republican Heritage Groups Council (NRHGC), which represents 5,000 ethnics in 26 nationality federations around the country. And the turnout was heartwarming, conservatively speaking.

Besides several of the new senators, such as Paula Hawkins of Florida, Alfonse D'Amato of New York and Jeremiah Denton of Alabama, there were Reagan foreign policy adviser Richard Allen, Health and Human Services Secretary-designate Richard Schweiker, Sens. Ted Stevens of Alaska and Robert Stafford of Vermont, former secretary of the Navy J. William Middendorf, the ambassadors of Japan and Korea and judo expert Jhoon Rhee.

Sharing the receiving line with Chennault were Sens. Orrin Hatch of Utah and Strom Thurmond of South Carolina, carrying on a spirited discussion over how to dress on Inauguration Day.

"Of all people, I thought you wouldn't desert us," Hatch, a dark-suit man himself, scolded Thurmond, of the morning-coat school. "We have to look our best," the South Carolinan replied. "It's the first time Republicans have had a chance to wear morning coats in 26 years."

Also in the receiving line (the waiters and busboys plowing through it at intervals on their way to the kitchen didn't really count) were Thurmond's wife Nancy and Christine Valmy, the Rumanian-born New York cosmetics company priestess who had promised her Rumanian friends "a bash" to get drunk at if Ronald Reagan won.

"I can't have people get drunk here," she said somewhat disconsolately, "so I'll have to have another bash."

Chennault, fighting a cold and lookung more like a wan swan than the legendary steel butterfly, got a kiss from Sen. Stevens, whose honeymoon she shared earlier this month when she, Stevens and his bride Catherine dropped in on the People's Republic of China for a meeting with Chinese Vice Premier Deng Xiaoping.

"A very fruitful trip," pronounced Chennault of her first trip to her native land since 1948. An outspoken critic of the Chinese Communist government through the years, she told how she and Majority Leader Howard Baker of Tennessee had been invited originally but when Baker's wife Joy became ill he designated Stevens, majority whip, as his substitute.

Deng Xiaoping, said Chennault was "certainly a very intelligent person" and while she was reluctant to talk about the specifics of the two-hour meeting she and Stevens had with him, she said "there was a great deal about their involvement in Vietnam, the Soviet Union, the Cultural Revolution and how after so many years of it they really have lost a generation.They felt they learned a lesson. I said, 'How can you prevent it from happening again?'"

Claiming that "no, I don't think I've had any change of heart' philosophically, Chennault called the Cultural Revolution "a very difficult thing. But at the same time I decided I'd never been ignorant about what happened in Mainland China."

Stevens, who had flown with Chennault's late husband Gen. Claire L. Chennault and his World War II Flying Tigers, said the question of selling U.S. arms to the People's Republic was one "we haven't gotten into yet, but we haven't ruled it out -- every time I'm asked to comment on that I get misquoted." He also said he and Chennault did not go there as official representatives of Ronald Reagan.

"The Chinese are very astute about the American political system, and they know better," said Stevens.

Richard Allen confidently predicted that Alexander M. Haig Jr. will be confirmed as secretary of state despite the current flap over releasing the Watergate tapes to the Senate Foreign Relations Committee. As to whether President-elect Reagan had approved the China journey of Chennault and Stevens, Allen said: "He doesn't take any position on foreign travel by anyone."

Across the room, one-time Navy secretary and sometime songwriter Middendorf was showing off a newspaper clipping about the official inaugural song called "Thumbs Up America" which he and lyricist Sammy Cahn unveiled this week.

"Hey," said Middendorf as if struck by the coincidence of it for the first time, "wasn't it Anna Chennault's husband who used to do thumbs up when he'd start down the airstrip on the Burma Run?"