Gov. Harry Hughes' proposed labor department passed the Maryland Senate today, after conservative senators who engaged in a night-long filibuster against it were assured that several measures, including two other labor-backed bills, would likely be killed.

The filibuster, which Senate President Melvin A. Steinberg said was "95 percent" resentment toward Hughes, was called off at 3:30 a.m. today, nearly 10 hours after the lenghty monologues against the Department of Employment and Training, as it is called, began.

The Senate then quickly approved, 33 to 12, the proposed new department, which now needs the endorsement of the House to become Maryland's 13th cabinet-level agency.

The department, which would consolidate several work programs and jobs in other state agencies, will be debated in the House but is expected to be approved. It will cost about $500,000 to start up, the bulk of which is federal money.

In exchange for ending the first filibuster of the 1983 General Assembly, the rural and Republican senators were told that two union-backed bills--making it easier for teachers' unions to call a strike and forcing state contractors to pay prevailing, and usually union scale, wages--are not likley to pass.

In addition, they were told that the Senate would not approve language in the House-approved budget suggesting Cecil County, on the Eastern Shore, as a possible site for a new maximum-security prison.

Cecil is the home of Sen. Walter A. Baker, the leader of the filibuster.

"I think everybody wanted to work this thing out and we did," said Baker after the filibuster had been dropped and the vote in favor of the new department taken. "Everyone was tired." Through most of the filibuster, senators slept on couches in the Senate lounge or in their chairs on the Senate floor.

Steinberg, who received little help from Hughes or his staff despite their claims that the department was the administration's top legislative priority, said that the agreement was reached after it became apparent that the senators involved were less concerned about the new department than other issues.

The Senate has a long and much honored tradition of permitting filibusters. Cloture motions to end debate generally fail to attract the necessary two-thirds majority--or 32 votes. Added to that during this filibuster was a lingering hostility toward Hughes caused by his politically aloof style, according to some senators.

"This bill doesn't mean anything to anyone," said Sen. Thomas V. Mike Miller (D-Prince George's), who was tallying votes for Steinberg through the early morning. "The only thing this filibuster is doing is embarrassing the governor."

The agreement reached this morning to end the filibuster did not please labor leaders. Representatives of the AFL-CIO, who helped elect Steinberg as Senate president, met in a stormy session with him this morning to hear the details of the filibuster-ending deal.

The teachers' strike bill would make optional the current requirement that school boards must decertify a union that engages in a strike, a language change that opponents say will encourage strikes. Steinberg told the conservative senators that he will work with them to kill the bill.

The Senate president also assured Baker that there was no support in the Senate or the governor's office for a new prison in Cecil County. The House two weeks ago decided that Hughes' decision to put the new prison in rural Somerset County, on the lower shore, should be reconsidered by examining sites in Cecil. Today, in keeping with the agreement, a Senate budget subcommittee stripped away all references to Cecil County and any other county in the appropriation for a new jail.