United Auto Workers union members, meeting at their international convention here, took a first step today toward reaffiliation with the AFL-CIO by authorizing a special merger convention sometime within the next six months.

The resolution passed despite a brief floor fight by delegates who fear that the special convention would be a prelude to reaffiliation, something many of them oppose. Thirteen UAW locals have filed statements opposing rejoinging the AFL-CIO. The reaffiliation move was supported by the UAW's new president, Douglas A. Fraser, who was sworn in today, and by his predecessor, Leonard Woodcock. The proposed special convention would take place only upon the recommendation of the UAW international executive committee.

Fraser described the proposed remerger with the AFL-CIO as the UAW's "duty and obligation to the labor movement." He said the UAW and the national labor federation already agree on "95 per cent of the issues before us."

But many rank and file delegates here disagreed with their new president and maintained that reaffiliation with the AFL-CIO would deprive the union of the independence it has enjoyed since Walter Reuther pulled the 1.4-million-member UAW out of the federation in 1968.

"Our thoughts and policies would be lost in the shuffle in a merger," said Charles Combs, vice president of Local 863 which represents Ford workers in the Cincinnati area. "The progressive thrusts of our policies would be completely lost."

Combs, whose local is among those opposing the affiliation, said his opposition like many others here was largely based on a dislike for AFL-CIO President George Meany.

"I think Meany's the main reason," Combs said. "He's a man whose time has passed nad he's a dictator who climbed in bed with Nixon. If they (AFL-CIO) got some new leadership our opposition might not remain."