The White House yesterday named Jennefer Austin Hirshberg, 42, currently director of the Federal Trade Commission's Office of Public Affairs, as press secretary to First Lady Nancy Reagan, effective next Monday.

Hirshberg has worked as a director of corporate communications for Bendix Automation in Cleveland, a media consultant with Gray & Co. in Washington, a reporter with the now-defunct Washington Star, a part-time rock music critic for The Washington Post and as an English teacher at Glendale (Calif.) Community College. She succeeds Sheila Tate.

She also looks like a movie star.

"The nicest thing anybody ever said to me was 'You know who looks just like you?' and I said, 'Who?' They said, 'Farrah Fawcett,' and I said, 'That's a twist -- it's usually the other way around,' " Hirshberg said yesterday in an interview.

Often mistaken for the star of the television series "Charlie's Angels," Hirshberg said it is not unusual for "a little old lady" to come up to her in a supermarket and ask, "Aren't you Farrah Fawcett?"

She said even CBS president William Paley once mistook her for Fawcett. She was covering a state dinner at the White House when Paley "came up to me, gave me a big hug and said, 'It's so nice to see you again,' " Hirshberg recalled, laughing.

She said she was never one of the so-called "Murray's Angels," a group of attractive, talented young women reporters hired by editor Murray Gart during the final hurrah of The Washington Star.

She said it was Gart, however, "who had faith in me. I was an unknown and he said, 'Here, go do it.' " She said she heard the news that The Star was folding when she was on her way to Andrews Air Force Base in July 1981, to fly to London with reporters covering Mrs. Reagan at the wedding of Prince Charles and Lady Diana.

"I quickly telephoned Murray Gart, who told me to go ahead with the trip. I did six stories in seven days. I got back on a Monday, did two more stories that week. Friday Aug. 7 was The Star's last day," Hirshberg said.

Generous with praise for her former bosses, Hirshberg said if she is the quintessential Washington success story, it is "less my success and more the success of other people" like Federal Trade Commission Chairman James Miller, Robert K. Gray of Gray & Co., Murray Gart and Fred Searby, president of Bendix Automation until his drowning death last year. She said that Nancy Reagan will be her first woman "boss" in her varied career within the communications field. She will report to deputy assistant to the president James S. Rosebush, the first lady's chief of staff, but will have direct access to Nancy Reagan.

"My job is as interpreter of Mrs. Reagan to the rest of world, and unless I can talk to her any time of the day or night it just wouldn't work. It will be the same working relationship that Sheila Tate has had," said Hirshberg, who will take a $12,000-a-year salary cut to succeed outgoing press secretary Tate in the $53,733a-year White House job.

"It may sound corny, but it's an opportunity to serve in a way I would never have had at another time," Hirshberg said. "One of my close friends at the Federal Trade Commission said, 'If the president called and asked me to come over and become his chief janitor, I'd say, "Fine, Mr. President. Do I get my own broom, where are my overalls and do I share a closet?" ' So you do it if you're asked."

"Mrs. Reagan is very happy about Jennefer's selection," said Tate, who leaves Feb. 15 to become a senior vice president in the Washington office of Burson-Marsteller, a national public relations firm.

Hirshberg said Tate, credited with turning Nancy Reagan's public image into that of a national spokeswoman against drug abuse, will be "a hard act to follow" but that that will be part of the challenge.

"There is a tremendous positive feeling for Mrs. Reagan. That will be something to sustain. There are bound to be little valleys and dips, so in some sense that would be the challenge," Hirshberg said.

A native of Jersey City, N.J., she grew up in Darien, Conn. She is the fraternal twin of Meredith Senold of Virginia and one of four children of James and Adele Austin. She is a graduate of Cornell University and received her master's degree from California State University at Los Angeles.

Divorced, she has one daughter, Eliote, 14, who attends private school here.