Leonore Annenberg, an active figure in the arts and wife of former ambassador to Great Britain Walter Annenberg, has been appointed the U.S. chief of protocol, the White House announced yesterday. The post carries the rank of amabassador and a salary of $50,112.

Annenberg, 62, reached yesterday in California, said, "I'm going to the State Department Tuesday, and I'll look into what I'm going to be doing. I will do my very best to see that I live up to what's expected of me."

Annenberg, whose friends calls her Lee, becomes the 19th chief of protocol and the third woman to hold the job. Preceding her were Shirley Temple Black, whom President Gerald Ford appointed, and Edith (Kit) Dobelle, whom President Jimmy Carter named to succeed her husband Evan.

Annenberg's husband the millionaire publisher of Triangle Publications, which includes TV Guide, served as U.S. ambassador to Great Britain for the Nixon administration from 1969 to 1974.

The chief of protocol is the main advance person for the president in state visits abroad and the United States' principal officer overseeing ceremonial functions here at home, including state and official visits of foreign leaders.

Annenberg does not know how much entertaining she will be doing, "It's one of the things I have to find out," she said."I enjoy entertaining. I look forward to meeting the foreign diplomats."

She said that President Reagan called her a couple of weeks ago with the offer, and she is still uncertain what the position will entail. "I haven't really gotten into the job," she said. "I have a big thick book in front of me with all the duties and regulations of chief of protocol."

Her husband will accompany her to Washington. "He said he would be very happy to come with me," Annenberg said. "He will run his business from Washington and Philadelphia, where he'll go on weekends."

Annenberg mentioned a variety of past experiences which she feels qualified her for the post. "After 5 1/2 years of being ambassadress -- that's what they call the wife of the ambassador in London -- you deal with one side of protocol every day. and being married to a publisher for some 30 years, I've met with important people, dealt with them, entertained them."

Annenberg also worked on the arrangements for Queen Elizabeth's stay in Philadelphia during the Bicentennial. "I worked for about six months planning her 24-hour stay in Washington." Annenberg said. "I worked with Protocol in Washington, I worked with the city, the police, the fire department. We planned every step from the minute she stepped off the yacht to the next morning that she left for Washington."

Annenberg sits on the board of directors of the Pennsylvania Academy of Fine Arts, the Philadelphia Orchestra, the Academy of Music and the Philadelphia Museum of Art. She is honorary trustee of the Performing Arts Council of the Music Center of Los Angeles County, and a director of the Metropolitan Opera Associates.

Morgan Mason, recently appointed deputy chief of protocol, said yesterday, "The key thing is that the chief of protocol have close relations with the first family, and Mrs. Annenberg does."

The Annenbergs are close friends of the Reagans, whom they traditionally entertain over New Year's at their multimillion-dollar estate in the Palm Springs, Calif. desert. They also have homes in Wynnewood, Pa., and Sun Valley, Idaho. Annenberg said that she and her husband expect to rent an apartment here.

Many observers regard Annenberg's appointment as a return to a long tradition of naming the wealthy and socially prominent to the protocol post, a tradition broken when Carter appointed the Dobelles and finally Abelardo Valdez to the position.

One Reagan insider, Harriet Deutsch, who has been a friend of Annenberg's since she was Leonore Cohn (her maiden name), said the new chief of protocol is" bright, capable, kind and as beautiful inside as she is outside. She ran that embassy in London, just superbly, knows many of the world leaders, which is a great plus. I'm happy for the country and for her."

"She'll add a lot of style to protocol," said James Kabler, a New York businessman who is married to Elizabeth, Lee Annenberg's daughter by a previous marriage. "She'll represent the Reagans well. I think Lee will be the best chief of protocol ever. She'll dedicate her full capabilities to the job. Her organizational skills are unsurpassed. She pays attention to detail.

"She's really thrilled," Kabler said, "and the fun thing for us will be when we get a phone call and someone says it's Ambassador Annenberg calling. We'll have to say, 'Which one?'"

Annenberg's father, Maxwell Cohn, and his brother Harry started Columbia Pictures. Harry Cohn and his wife raised Annenberg after her mother died when Annenberg was very young.

"She's very active in cultural activities," Kabler said. As for her qualifications: "What qualified Henry Catto? What qualified Shirley Temple Black?" asked Kabler.

Former protocol chief James Symington, appointed by Lyndon Johnson in 1966, said yesterday, "It's already been shown that women can handle the job -- that obstacle has been removed from the public and diplomatic perception of it." He said that Annenberg probably has already met half of the people she will be dealing with.

But with the sanctity of the diplomatic community clearly threatened throughout the world, the administrative load which a chief of protocol faces is a significant responsibility, Symington said.

Abelardo L. Valdez, an attorney who held the position for the last 18 months of the Carter administration, estimated yesterday that 50 percent of his time was spent as principal liaison to the 142 embassies here and to the 1,000 consulates around the country, on legal problems involving diplomatic immunity and privileges, and on relations with local governments involving diplomats. Social obligations, he said, probably accounted for less than one-third of his time.

"It was probably the most physically demanding job I've ever had," Valdez said, "except for being a migrant laborer."