Warren Beatty became the first quadruple Oscar nominee since Orson Welles -- for "Citizen Kane" in 1941 -- when the finalists for the 51st annual Academy Awards were announced yesterday in Los Angeles.

Beatty produced one of the nominees for best film, "Heaven Can Wait" -- the sentimental comedy about a proquarterback brought back to life after a premature demise. He was also nominated as best actor for his starring role in that film, and could share awards with co-director Buck Henry in the directing category and cowriter Elaine May for best screenplay adapted from material originated in another medium.

"The Deer Hunter," a brooding epic about three friends from a Pennsylvania mill town who serve in Vietnam, and "Heaven Can Wait" led all contenders for 1978 awards with nine nominations each. ("The Deer Hunter" will not go into national release until this Friday, but received special one-week engagements in Los Angeles and New York in December to qualify for the 1978 awards.)

The leaders were trailed by "Coming Home," a romantic triangle involving a Marine officer, his wife and a paraplegic Vietnam veteran, with eight nominations, and "Midnight Express," a sensationalistic account of an American student's imprisonment in Turkey for drug smuggling, with six nominations. These four were joined by "An Unmarried Woman," the story of a wife's response to the sudden collapse of her marriage, as nominees for best film of 1978.

Beatty's competition for best actor consists of Laurence Olivier in "The Boys from Brazil," Robert De Niro in "The Deer Hunter," Jon Voight in "Coming Home" and Gary Busey in "The Buddy Holly Story." Olivier, nominated for the 11th time, won best actor in 1948 for "Hamlet" after receiving a special award two years earlier for "Henry V."

Two weeks ago the board of governors of the Motion Picture Academy of Arts and Sciences announced that Olivier would receive a second honorary Oscar at this year's ceremonies "for the full body of his work, for the unique achievements of his entire career and his lifetime contribution to the art of film."

De Niro won the 1974 award for best supporting actor in "The Godfather, Part II." He was nominated as best actor for "Taxi Driver' in 1976. Voight was previously nomipated for "Midnight Cowboy" in 1969. Busey received his first nomination.

Ingrid Bergman, a three-time Oscar winner, was nominated for an unprecedented fourth as best actress for her performance in Ingmar Bergman's "Autumn Sonata." The other nominees are Ellen Burstyn in "Same Time, Next Year," Jane Fonda in "Coming Home," Jill Clayburgh in "An Unmarried Woman" aid Geraldine Page in Woody Allen's Bergmanesque chamber drama, "Interiors."

Ingrid Bergman was named best actress for "Gaslight" in 1944 and "Anastasia" in 1956, and won supporting actress in 1974 for "Murder on the Orient Express." Burstyn and Fonda are previous winners -- for "Alice Doesn't Live Here Anymore" in 1974 and "Klute" in 1971, respectively. Page has now been nominated three times each as best actress and supporting actress but has yet to win. Clayburgh is a first-time nominee.

Maggie Smith, named best actress in 1969 for "The Prime of Miss Jean Brodie," has the opportunity for a rare double with her nomination as supporting actress in "California Suite," where she played a jittery Oscar nominee. The other four candidates are previous nomipees Dyan Cannon in "Heaven Can Wait," Maureen Stapleton in "Interiors," and newcomers Meryl. Streep in "The Deer Hunter" and Penelope Milford in "Coming Home."

The finalists for best supporting actor include only one previous nominee, Jack Warden, for his work in "Heaven Can Wait." The other nominees are Bruce Dern in "Coming Home," Richard Farnsworth in "Comes a Horseman," John Hurt in "Midnight Express" and Christopher Walken in "The Deer Hunter."

In addition to Beatty and Henry in "Heaven Can Wait," the candidates for best direction will be Hal Ashby for "Coming Home," Michael Cimino for "The Deer Hunter," Alan Parker for "Midnight Express" and last year's prize-winner, Woody Allen, for "Interiors."

The year's top box-office attraction, "Grease," received only one nomination: best song for the melancholy ditty "Hopelessly Devoted to You." Lorraine Gray's "With Babies and Banners: Story of the Women's Emergency Brigade," produced by the Washington-based Women's Labor History Film Project, received a nomination as best feature documentary. (The film is scheduled for special showings today, Thursday, Saturday and Sunday at the Biograph.)

The 51st Academy Awards will be announced on Monday, Apr. 9, at ceremonies in the Dorothy Chandler Pavilion of the Los Angeles Music Center. Johnny Carson will be the solo emcee for this year's Oscar show, telecast live by ABC. Nominations are determined by balloting within the various branches of the Academy, a professional orgahization administered by the film guilds and unions. The entire membership of about 3,500 votes for the final awards. Official screenings of nominated films begin Saturday at the Academy's Samuel Goldwyn Theater in Los Angeles. Final ballots will be mailed on Mar. 20.

Within the movie community exhibition on "Z Channel," a subsidiary of Theta Cable, a pay-TV system whose 89,000 subscribers include a sizable percentage of Hollywood professionals and/or Academy members, has acquired an importance commensurate with official Academy screenings.

Many insiders attribute the Oscar success of "Annie Hall" last year to its long availability and consistent popularity on "Z Channel," which normally provides customers with about a dozen recent movies a month for a monthly fee of $19.95. Only one of the six major companies, Universal, which is distributing "The Deer Hunter," still declines to book contending features on "Z Channel."