Bipartisan members of the Joint Economic Committee, planning to take up President-elect Ronald Reagan on his pledge to cooperate with Congress, said yesterday they hope to use the results of an economic conference next week as the basis for congressional economic policy recommendations to the incoming administration.

JEC Chairman Lloyd Bentsen (D-Texas), at a news conference with Republicans Sen. William Roth (R-Del.) and Rep. Clarence Brown (R-Ohio), said that as president-elect Reagan has shown "enthusiastic interest" in working with Congress, he and other members of the JEC hope to respond by giving their proposals for economic policy.

He and Roth disagreed on whether Reagan was likely to remain committed to a three-year plan of cuts in personal tax rates. Roth has sponsored this with Rep. Jack Kemp (R-N.Y.), and said he would vigorously promote the Kemp-Roth plan in the next Congress and expected Reagan to support it. Bentsen said that there probably would be significant changes in the Republican plans before they were finally announced in the State of the Union address.

The JEC has pushed for "supply-side" economics -- which centers around cutting marginal tax rates for individuals and giving tax breaks to business -- and Bentsen said that its bipartisan support for these ideas had had a marked effect on Congress. He and the others said they hoped that their new recommendations on how to deal with the problems of inflation and unemployment would have an impact too.

The participants in the conference will include some members of Reagan's orbit such as Alexander Haig, now being mentioned as a possible secretary of State; Richard Allen, a senior foreign policy adviser; Murray Weidenbaum; and Charls E. Walker.

Keynote speakers will include Lane Kirkland, president of the AFL-CIO, and William Batten, New York Stock Exchange chairman. The 100 or so participants will include "Republicans and Democrats, and senior representatives of labor, business, consumers, minorities and environmental groups," Bentsen said.

Although they may not reach a concensus on economic policy he told reporters that the JEC would distill the comments on the conference into a written report to be sent to the president-elect.