CHARLES G. BLUHDORN, THE HEAD OF GULF AND WESTERN, DIES AT 56

Charles G. Bluhdorn, who built a small Michigan auto-parts company into Gulf and Western Industries, the multibillion-dollar conglomerate, died yesterday while flying home to New York from a business trip in the Dominican Republic. He was 56 years old and lived in Manhattan.

Jerry Sherman, an assistant vice president and director of public relations for G.&W., said Mr. Bluhdorn, the company's founder, chairman and chief executive, was aboard a corporate plane when he died. Mr. Sherman said the cause of death was a heart attack.

Mr. Bluhdorn built the giant business, which in 1981 ranked 61st among the Fortune 500 corporations in the United States, out of a small auto-parts manufacturing company in Grand Rapids that he acquired in 1956.

Two years later, after a merger with a Houston automotive-parts distributor, Gulf and Western Industries was formed. In its first year as G.&W., the company reported a net loss of $730 on sales of $8.4 million. 'Strong-Willed' Executive

A quarter-century later, after a spectacular chain of acquisitions and growth during the late 1960's and early 70's, the conglomerate reported sales in 1982 of $5.3 billion and earnings from continuing operations of $199 million.

Martin S. Davis, a business associate of Mr. Bluhdorn since 1965 and an executive vice president at G.&W. since 1974, described Mr. Bluhdorn as a ''strong-minded and strong-willed'' chief executive, who nonetheless was ''always willing to hear the other side of an argument.''

Mr. Bluhdorn's favorite expression, on issues as well as on dollars, Mr. Davis said, was, ''What is the bottom line?'' Although Mr. Bluhdorn exerted strong control on major decisions, Mr. Davis said, he built a strong management team during the years of the company's growth and ''was willing to delegate authority.''

The company, with assets in 1982 of $5.8 billion, employs more than 100,000 workers, primarily in the United States and the Dominican Republic, where G.&W. has vast sugar holdings. Its corporate headquarters, a prominent feature of the New York skyline, is a 42-story office tower just off the southwest corner of Central Park, at Columbus Circle. Highly Diversified Operations

G.&W.'s highly diversified operations are divided into leisure time, financial services, consumer products, manufacturing, food products, automotive and building products and natural resources.

Among its hundreds of subsidiaries, the most widely known are Paramount Pictures, the Madison Square Garden Corporation and Simon & Schuster, the publisher.

In 1979, after a three-and-a-half-year investigation, the Securities and Exchange Commission filed a civil complaint against G.&W., Mr. Bluhdorn and Don F. Gaston, executive vice president, charging them with improper financial reporting and other ''fraudulent courses of conduct.''

When the S.E.C. filed its complaint, Mr. Bluhdorn called the charges ''totally unwarranted and outrageous'' and vowed ''to litigate this matter to the end.''

Two years later, as part of a settlement, G.&W. agreed not to violate antifraud and reporting provisions of the Federal securities law and to strengthen the company's bylaws.

Mr. Bluhdorn owned slightly more than 5 percent of G.&W.'s common stock. Born in Vienna on Sept. 20, 1926, Mr. Bluhdorn emigrated to the United States in 1942. After service in the Army Air Forces, he studied at the City College of New York and Columbia University but did not earn a degree.

He began his career in a New York cotton brokerage house, earning $15 a week. In 1949, he formed an import-export concern that he operated until, at the age of 30 and already a millionaire, he bought into the Michigan parts company.

His first major acquisition as head of G.&W. was the New Jersey Zinc Company in 1966, with Paramount Pictures following the next year. Active in Civic Affairs

A trustee of Texas Wesleyan College and the Trinity Episcopal Schools Corporation in New York, Mr. Bluhdorn served in many other civic capacities over his years as a prominent corporate executive.

In 1977, Mr. Bluhdorn announced that G.&W. would buy the New York Cultural Center on Columbus Circle and give it to the city, which it did in 1980.

Surviving are Mr. Bluhdorn's wife, the former Yvette M. LeMarrec; a son, Paul, and a daughter, Dominique, both of Manhattan, and a sister, Inga Tiger of Chicago.

A private funeral will be held tomorrow.