Rep. Jack Brooks (D Tex.) concluded House hearings on government reorganization legislation yesterday conceding he had little chance to win his fight with President Carter on how it should work.

Carter wants the same power given all postwar Presidents through Richard M. Nixon's first term to reorganize federal agencies in interests of efficiency unless one house of Congress vetoes his plan within 60 days of submission. Brooks contends that this reverses the constitutional role of Congress as legislator and wants the plans to take effect only if a majority of both houses of Congress approves them.

Brooks spent yesterday morning listening to witnesses side with him against the President, but also heard a majority of his subcommittee, including Republicans, support the President's approach.

After the hearing, Brooks said he was "not too optimistic" about winning the basic issue in the subcommittee, in the parent Government Operations Committee, which he also heads, or on the House floor.

"This is the first pitch by a new President and everyone wants to get along with him," said Brooks. "It would be nice if I could. We just have an honest difference of opinion."

The Senate sided with Carter on the one-house veto, approving its version of the reorganization powers bill last week. Brooks said he hopes the House will adopt some changes, such as making it easier to get floor votes on reorganization plans.

Rep. John E. Moss (D-Calif.) said he has been opposed to the concept of reorganization plans that Congress may not amend ever since he came to the House in 1953 and opposed a reorganization plan that created the Department of Health, Education and Welfare. He called HEW a "unique monster of modern government." Moss said he believed Congress would never have enacted a law creating the huge department if it had made the careful inquiry that goes into writing legislation.

Moss said he knew of no reorganization plan that has made any improvement in government. He preferred Brooks' approach requiring affirmative action by Congress, but didn't really like that either because he believes Congress should be able to amend a presidential plan to reorganize the government.

Philip B. Kurland, law professor at the University of Chicago and a constitutional specialist, opposed the President's plan as unconstitutional.

"It is for Congress to write the laws," said Kurland. "I know of no way constitutionally to justify such a process" as Carter's proposal. He quoted favorably Brooks' contention that it would "stand the Constitution on its head."

"I am at a loss to understand why it is necessary to exlude Congress from formulating reorganization plans," said Kurland. "Why should a President draft a plan secretly and spring it on Congress? I don't understand it. I fear it."