Congress began formal hearings yesterday on the Humphrey-Hawkins "full employment" bill, with sponsors hoping to push it through both houses promptly in part as a memorial to the late Sen. Hubert H. Humphrey (D-Minn.).

A House Education and Labor subcommittee headed by the bill's other original sponsor, Rep. Augustus F. Hawkins (D-Calif.), heard a series of witnesses supporting the bill, including Coretta Scott King, widow of the slain civil rights leader.

Hawkins told reporters he had reached agreement with the House leadership to have the measure on the House floor in time for a vote by March 1 - almost a month earlier than sponsors had hoped previously.

Passage is expected to come easily in the House, in part because of sentiment to take action in Humphrey's memory. The outlook in the Senate is somewhat less certain, although sponsors say they are optimistic.

The compromise legislation, a watered-down version endorsed reluctantly by the White House, would commit the government symbolically to reducing the jobless rate from its present 6.4 per cent to 4 per cent by 1983.

Although the bill no longer would force the government to set up programs for reaching that goal, it has been criticized by economists of both parties as unrealistic. Experts say reaching the target would exacerbate inflation.

President Carter endorsed the bill in November after several months of negotiations over changes from the earlier bill.

Yesterday's hearing was marked by frequent references to Humphrey, with Irving Bluestone, vice president of the United Auto Workers, recalling that Humphrey's "very last words to the nation urged us to get on with" the bill.

Bluestone told the hearing that if Humphrey "could speak to us today, . . . he would remind us that we could honor him best by not composing eulogies . . . but by remaining steadfast in the causes to which he devoted his life."

And Andrew J. Biemiller, legislative director of the AFL-CIO, which also supports the bill, told the panel his group could think of "no greater or more lasting memorial to Hubert Humphrey."

One uncertainty still plaguing sponsors of the measure is who will shepherd the legislation in the Senate in the wake of Humphrey's death.