Jacob M. Arvey, 81, Chicago's Democratic boss in the post World War II years, who was influenced in national politics and enjoyed a reputation for enlightened leadership, died yesterday in a Chicago hospital.

The cause of death was listed as "a recurrent heart attacks."

In great degree, Mr. Arvey's reputation rested on the candidates he supported. In 1948, as head of the almost legendary Cook County Democratic party organization, he played a key role in sending Paul Douglas to the U.S. Senate and making Adlai Stevenson governor of Illinois.

Later Mr. Arvey was credited with helping engineer Mr. Stevenson's nomination for the presidency.

As the boss of the political machine - a 1951 political column said he had been perhaps the most powerful in the country - Mr. Arvey held power through shrewd calculation and meticulous attention to detail.

One of his major miscalculations came in 1948, when he supported Dwight D. Eisenhower for the Democratic presidential nomination.

After the convention, however, he worked wholeheartedly in behalf of President Truman. When returns showed that Mr. Truman had carried Illinois by a narrow 33,612-vote margin out of almost 4 million votes cast, Mr. Arvey was hailed as a principal architect of victory.

In 1948, Mr. Arvey also was instrumental in winning adoption at the convention of the strong civil rights plank in the party's platform.

In a key maneuver during discussion of the rights proposal, Mr. Arvey, a relatively slight man of 5 feet 6, was carried on the shoulders of the taller and huskier Paul Douglas to a vantage point near the podium, from which he could address the chairman.

A native of Chicago, Mr. Arvey studied law at night at the John Marshall Law School, and began clerking a $5 a week in a law firm with strong political ties.

Quickly involving himself in politics, he became an alderman in 1923, and in 1934 became ward committeeman - "boss" in fact - of the 24th ward, which soon became one of the strongest Democratic bastions in the entire nation.

In the 1924 presidential race, Mr. Arvey's largely Jewish ward to the south and west of Chicago's center voted Republican. In 1936, the vote was 26,112 for Franklin Roosevelt, and only 974 for Alfred M. Landon, and Mr. Arvey had clearly become a major force in Chicago politics.

In January, 1941, he joined the Army, at the age of 45, partly, he once said, as an escape from organization politics. After returning home from World War II service in the Pacific as a lieutenant colonel, he was offered the chairmanship of the strife-ridden Cook County Democratic committee.

As boss, Mr. Arvey replace longtime mayor Ed Kelly with reform minded Martin Kenelly.

Despite his successes, Mr. Arvey proved unable to maintain his power, and his star declined as that of Richard J. Daley ascended. In 1950, Mr. Arvey's local candidates met disastrous defeat, and Mr. Arvey stepped down as county chairman. He became a member of the Democratic National Committee, serving until 1972.

In addition to his wife, Edith, he is survived by two sons, Howard and Erwin, and a daughter, Helen Sue Bresky.