Arnold R. Miller, 62, the former president of the United Mine Workers Union who wrested control of the organization from the late W.A. (Tony) Boyle on a reform platform in 1972, died yesterday at Charleston Area Medical Center in Charleston, W.Va. He had suffered from black lung disease, heart ailments and strokes.

Mr. Miller was a coal miner and the son and grandson of coal miners, and he brought an unprecedented degree of democracy and internal reform to the 270,000-member UMW. Ironically, his seven-year presidency ended amidst charges that Mr. Miller himself had become dictatorial in managing union affairs.

Forced out of the mines in 1969 by a combination of black lung disease, arthritis and high blood pressure, Mr. Miller first came to public attention when he led a group of coal miners in a successful campaign to persuade the West Virginia legislature to enact a program of compensation for coal miners who suffered from black lung.

That period was a time of ferment within the UMW, which historically had been operated almost as a personal fiefdom of the union president, Boyle, and before him, the legendary John L. Lewis.

A union insurgent, Joseph (Jock) Yablonski, had challenged Boyle in an election, arguing that he was authoritarian, corrupt and indifferent to the plight of rank-and-file miners. Boyle won that contest. Yablonski vowed to challenge the results in court, and three weeks later he was murdered in his home in Western Pennsylvania along with his wife and daughter.

Mr. Miller inherited the mantle of reform from Yablonski and with the backing of Yablonski's family and supporters was elected president of the union in 1972, several months after a federal judge overturned Boyle's 1969 victory on the grounds that he had violated federal labor laws.

Boyle subsequently was convicted of Yablonski's murder, and he died in prison last May 31.

A soft-spoken but determined man, Mr. Miller presided over a series of union reforms. With the support of Yablonski's son, Joseph A. (Chip) Yablonski Jr., and Washington lawyer Joseph L. Rauh Jr., he quickly instituted a number of procedures previously unknown to most miners. They included the right of members to vote on the ratification of contracts, the election of district officers and executive board members, and a wide-open union newspaper.

But it was not long before Mr. Miller himself became the target of criticism that he had become dictatorial, and many of his old supporters in the reform movement broke with him. Mr. Miller was said by his critics to have lost touch with the rank and file, to have insulated himself within the UMW office in Washington, and to have become too enamored of the perquisites of his position, including a nine-seat Cadillac he rented to enhance the prestige of the union presidency.

In 1977, Mr. Miller was reelected union president, but with a different slate of officers from the reform group that had backed him five years earlier. Soon afterward ill health began to take its toll. He was working 16 to 18 hours a day and sleeping no more than four or five hours a night, partly because black lung disease made it difficult for him to breathe when lying down. There were wildcat strikes in the coalfields, a sign of weakness in union discipline.

In 1978, the UMW went on strike for 110 days. Mr. Miller twice recommended that members ratify contracts he had negotiated and twice the membership refused. The issue finally was settled, but Mr. Miller suffered a stroke and a heart attack in the wake of the affair.

Union dissidents began gathering signatures on petitions for Mr. Miller's recall, but that movement collapsed when the UMW executive board ruled that improper procedures had been followed. In the end, Mr. Miller stepped aside. Citing his rapidly deteriorating health, he resigned in November 1979, turning the job over to Sam Church Jr., a former Boyle supporter who had been elected a UMW vice president on the slate with Mr. Miller in 1977.

Born in Leewood, W.Va., Mr. Miller began working in the coal mines when he was 16, after having left school upon completion of the ninth grade. He served in the Army during World War II and was wounded during the Normandy invasion. He returned to the coal fields after the war.

"I worked in low coal the more than 20 years I was in the mines," Mr. Miller said in a 1978 interview. "The last two years of that time I worked in mud and water and that really is what wiped me out. It was always cold and wet down there. I developed spinal arthritis, and it got so bad, finally, I couldn't even sleep at night."

Richard L. Trumka, president of the UMW since 1982, praised Mr. Miller in a statement yesterday as "a fitting example for all of us in the United Mine Workers of America.

"Possibly Mr. Miller's greatest achievements were the internal reforms he instituted within our union and the historic breakthrough he led in the area of black lung legislation," Trumka said.

Mr. Miller's marriage to the former Virginia Brown ended in divorce. Survivors include a son, Larry A., of Cross Lanes, W.Va.; a daughter, Vickie L. Miller of Chelyan, W.Va.; a brother, Clarence Edward, of Victor, W.Va.; two half sisters, Mary Braden of Ohley, W.Va., and Norma Oroszi of Alexandria; and one grandson.