Pat Nixon, the quiet consort who stood by her husband, Richard M. Nixon, in the White House and out, through victory, defeat, sorrow and illness, died yesterday at their home in Park Ridge, N.J. She was 81.

Mrs. Nixon, who had been ill for several years, died of lung cancer, said Kim Taylor, a spokeswoman for the Nixon family.

She said former President Nixon and the Nixons' two daughters, Tricia Nixon Cox and Julie Nixon Eisenhower, were with Mrs. Nixon when she died at 5:45 A.M. She also said that Mr. Nixon, who visited Russia in February and China in April, was "in excellent health as evidenced by his recent travel schedule."

Commenting on Mrs. Nixon's death, former Secretary of State Henry A. Kissinger said, "Pat Nixon was an extraordinarily supportive First Lady, particularly good in her judgment of people."

Former President Ronald Reagan issued a statement that Mrs. Nixon was "a pillar of great strength during a time of turmoil." Dislike of Politics

On the eve of Richard Nixon's inauguration as President in 1969, Pat Nixon was asked if she had ever encouraged her husband to enter politics.

"No," she replied. "I did not. Politics was not what I would have chosen for him because, after all, you don't see as much of your husband as you would like and it's a hard life."

But, she went on, Mr. Nixon was convinced that politics was his duty.

"What could I do?" she said.

What Mrs. Nixon did was subjugate her instinct for privacy and homemaking and become her husband's faithful companion in his turbulent years in the political arena, from the happy early years after his election as United States Representative from California in 1946 until his humiliating resignation as President of the United States in August 1974, under the shadow of impeachment proceedings that grew out of the Watergate scandals.

In Mr. Nixon's years as Representative, Senator, Vice President, candidate for governor of California, Presidential candidate and President, his wife was a fixture at his side, always seeming to listen raptly to his speeches and maintaining a gracious, if thin, smile.

In 1968, the writer Gloria Steinem interviewed Mrs. Nixon aboard an airplane while she was accompanying her husband on the Presidential campaign. In the New York magazine article, Ms. Steinem quoted Mrs. Nixon as saying: "Now, I have friends in all the countries of the world. I haven't just sat back and thought of myself or my ideas or what I wanted to do. Oh no, I've stayed interested in people, I've kept working. Right here in the plane I keep this case with me, and the minute I sit down, I write my thank-you notes. Nobody gets by without a personal note. I don't have time to worry about who I admire or who I identify with. I've never had it easy. I'm not like all you . . . all those people who had it easy." Image as President's Wife

Although her years before the public exceeded those of her two predecessors at the White House, Mrs. Nixon did not seem to stamp her personality on the nation's consciousness. Instead, her image was of a private, dutiful wife seemingly self-contained and impenetrable.

Her composure rarely wavered in her appearances with her husband in such trying circumstances as his televised Checkers speech in 1952, when he denied unethical use of an $18,000 political fund ("Pat doesn't have a mink coat"), the ordeal in Caracas, Venezuela, in 1958, when a stone-throwing, spitting, anti-American mob besieged the Nixon limousine; and the Nixons' grim, hand-in-hand walk down a red carpet from the White House after his resignation on Aug. 9, 1974.

Despite the early traumas and Mrs. Nixon's wish that her husband retire from politics, she was enthusiastic enough on the eve of his nomination as the Republican Presidential candidate in 1968 to say, "This really is the American dream, where people from humble circumstances can, through sheer hard work, go up the ladder." Humble Origins in West

Her own origins had, indeed, been humble. She was born Thelma Catherine Ryan on March 16, 1912, in the small mining town of Ely, Nev. Her father, William, an itinerant miner of Irish-American ancestry, gave her the nickname Pat because of her birth on the eve of St. Patrick's Day.

Before she was a year old, her mother, Kate, a German-born woman with a son and daughter from a previous marriage, prevailed on her husband to leave the mines. The family moved to Artesia, Calif., about 20 miles southeast of Los Angeles, and started a truck farm on a four-acre plot that had little plumbing and no electricity.

"We all worked hard," Mrs. Nixon recalled years later. "We dug potatoes, we picked tomatoes, we picked peppers, cauliflowers and peanuts."

In 1924, when Pat was 12, her mother died of cancer.

"For the last two or three months I used to sit with her through the night," she said years later. "We couldn't afford a night nurse and she needed attention."

Five years after her mother's death, Pat's jolly, blue-eyed father, whom she adored, died of the miner's disease, silicosis. Cross-Country Trip

The five children in the family soon split up. Pat, at the age of 18, at the height of the Depression, set out for New York, driving an elderly couple across the country in their Packard.

For two years, until 1932, she worked in New York as a secretary and X-ray technician. The money she saved eventually got her back to California and into the University of Southern California, where her major was merchandising. Walk-on parts on Hollywood movie sets helped finance her education.

She graduated cum laude in 1937 and tried unsuccessfully to find work as a buyer for a department store. So she took a job at $190 a month teaching shorthand and typing at a secondary school in Whittier, Calif.

She was also interested in amateur theater, and at auditions for the play "The Dark Tower" one night in 1938, she met Richard M. Nixon, a recent graduate of Duke Law School who had set up practice in Whittier.

Both won parts in the play that night, and the young Nixon proposed to her a few hours later.

"I thought he was crazy," she said in 1969.

Mr. Nixon courted her for two years, sometimes even driving her to meet other beaus, before she accepted the proposal. Married in Riverside

They were married June 21, 1940, in a Quaker ceremony in Riverside, Calif. The bride was 28 years old, and Mr. Nixon was 10 months younger.

After finishing his naval service in 1945, Mr. Nixon decided to run for the House of Representatives. Just before the campaign started, the Nixons' older daughter, Patricia (Tricia), was born, on Feb. 21, 1946. In Representative Nixon's first term, another daughter, Julie, was born, on July 5, 1948.

Two years later, Mr. Nixon began a successful campaign for the Senate. While he generated controversy with his anti-Communist campaign speeches, his wife was portrayed in the press as projecting what would later be called a "20th-century born-in-a-log-cabin image."

She also began projecting the image of game and gracious campaigner, always able to suppress distress and bitterness.

As the President's wife, Mrs. Nixon traveled more than 100,000 miles, campaigning for her husband, accompanying him to foreign countries and, on several occasions, representing him at ceremonies abroad. Foreign Affairs Duties

She was the first wife of a President designated to head a United Nations delegation abroad, to the inauguration of President William R. Tolbert Jr. of Liberia in 1972. She also visited Peru in 1970 to see areas devastated by an earthquake, and in early 1974 she headed the United States delegation to inaugural ceremonies for the Presidents of Brazil and Venezuela.

Mrs. Nixon promoted various education programs and sought to enlist Americans in volunteer aid programs.

She shied away from adopting any publicity-inspiring projects like Jacqueline Kennedy's historical redecoration of the White House. Instead, she seemed to enjoy a more traditional and limited role in the White House, as Bess Truman and Mamie Eisenhower had.

Nixon White House receptions and dinners were frequent, but small and sedate, with none of the exuberance of the Kennedy and Johnson Presidencies. Only in receiving-line chitchat and in quiet little teas and receptions at the mansion did the real warmth and thoughtfulness of Mrs. Nixon's personality emerge. Seclusion at San Clemente

After her husband's resignation, Mrs. Nixon remained in seclusion for nine months with him at their estate in San Clemente, Calif., and moved to New York in 1980.

In the summer of 1976, Mrs. Nixon suffered a stroke that partly paralyzed her left arm and leg and the left side of her face for about a year. She had another stroke in the early 1980's and fully recovered from it, too. But in recent years she was very frail and suffered from emphysema, and she was hospitalized several times for lung problems, said Kathy O'Connor, Mr. Nixon's chief of staff.

Besides her husband and her daughters, Ms. Cox of Manhattan, whose husband, Edward F. Cox, is a lawyer, and Ms. Eisenhower of Berwyn, Pa., whose husband, David Eisenhower, is a military historian and grandson of President Dwight D. Eisenhower, Mrs. Nixon's survivors include two grandsons, Christopher Nixon Cox and Alex Richard Eisenhower, and two granddaughters, Melanie and Jennie Eisenhower.

A service for Mrs. Nixon with family members and friends attending will be held at 10 A.M. Saturday in the Richard Nixon Library and Birthplace in Yorba Linda, Calif., with the Rev. Dr. Billy Graham presiding and eulogies by Senator Bob Dole, Republican of Kansas, and others. A private burial service will follow on the grounds of the library.

Mrs. Nixon's body will lie in state at the library on Friday. The public will be admitted from 5 P.M. to 9 P.M.

Patricia R Nixon