Annual congressional sparring about a "subminimum" wage for teen-agers began yesterday with Labor Secretary William E. Brock urging the Senate to pass it and House Democrats declaring it dead on arrival unless it is linked to increased spending for job training.

"The idea deserves to be tested," Brock told the Senate Labor and Human Resources Committee, referring to the proposed three-year test of lowering the minimum wage from $3.35 to $2.50 an hour for 16-to-19-year-olds in the summer.

"We have tried everything, and it hasn't worked" to reduce youth unemployment, Brock said. "It is unacceptable and inexcusable that we, as a society, have not addressed a problem that affects our own children."

But House Education and Labor Committee Chairman Augustus F. Hawkins (D-Calif.) and other Democratic opponents told reporters that, while the measure will benefit employers, it will create more problems by encouraging layoffs of older workers, discriminating against youngsters and depressing wages.

The Labor Department estimates that the measure would create 400,000 summer jobs and help remedy teen-age unemployment that ranges nationwide from 16 percent for whites to 42 percent for blacks. Opponents, including the AFL-CIO and the NAACP, say the job-creation estimates are inflated. Hawkins, who has proposed a youth employment and training bill with an estimated $2 billion price tag, said he met last week with Brock and agreed to "negotiate" the subminimum wage. But he said the Reagan administration's commitment to solving youth unemployment "is nothing more than rhetoric" unless coupled with expanded training.

Labor Department sources said Brock is willing to negotiate an acceptable solution with House and Senate leaders but said the likelihood of new job-training money is slim. "But we will be talking, and that is progress," a Brock aide said.

Chicago Mayor Harold Washington and District of Columbia Mayor Marion Barry took opposite sides of the issue yesterday. Barry, president of the National Conference of Black Mayors, testified that the group of 290 mayors endorses the program because "a job paying $2.50 an hour beats no job at all."

Barry said they endorsed the idea "out of frustration and desperation . . . because we are the ones on the front lines every day, who see the lack of hope" among jobless youth. Washington, appearing with Hawkins, said the "basic premise is faulty" because it is lack of training rather than wage levels that prevents minority youths from obtaining jobs.

Employers can hire youths at low cost by using targeted jobs tax credits that reduce labor costs to as little as 50 cents an hour in some cases, AFL-CIO legislative director Ray Denison testified. Despite this incentive, employers are reluctant to hire disadvantaged youths because they lack skills, he said.

Brock said a recent U.S. Chamber of Commerce survey showed that 49 percent of employers said they would hire youngsters at a lowered minimum wage. The chamber, the Boys Clubs of America, the National Farm Bureau, the American Legion and other organizations endorsed the lowered wage in statements submitted yesterday.

Committee Chairman Orrin G. Hatch (R-Utah) described the measure as "a simple and obvious way" to help remedy the problem at "no cost to the taxpayer." He said the Senate will pass the bill.