Four Pennsylvania Republican legislators from Philadelphia were being guarded by state troopers today after they claimed their lives were threatened because they refused to vote for a Democratic state budget proposal.

The legislature's inability to pass a budget has cut off checks for hundreds of thousands of welfare recipients and state employees.

Angry welfare recipients stood in the rotunda of the Capitol today and burned effigies of legislators who they believe are responsible for the state's fiscal crisis, in its seventh week.

State troopers, some in uniform and others in plain clothes, moved throughout the cavernous building to keep an eye on the demonstrators and provide protection for the four Republicans.

"People are crazy," said state Rep-Frank A. Salvatore, one of the legislators whose lives allegedly were threatened. "This is wrong. Things aren't supposed to go like this."

Salvatore said the threats were made Monday evening in anonymous telephone calls to a Philadelphia radio station and the Philadelphia Inquirer. He said he did not know who made the threats.

However, Salvatore said he believes that the threats were prompted by Gov. Milton J. Shapp's "viuperative attacks" on Republicans who have refused to go along with his budget proposals.

Shapp "issues statements designed to castigate we four Philadelphia Republicans legislators - to agitate people to put pressure on us - to make the people of Pennsylvania believe that we are the sole reason he is failing," Salvatore said.

"The governor's personalized and partisan attacks upon us has, as he planned created an emotional disturbance within the ranks of those who are being hurt in this budget impasse. And his ill-tempered outbursts have also triggered someone of criminal or deranted nature to threaten the lives of us and of our families," he charged in a press conference.

Many Democrats disavowed his accusation, often labeling it "ridiculous."

At the heart of the dispute is a proposed $5.1 billion budget that would fund general state operations but would leave unfunded state-related colleges, private colleges and medical schools. The state Senate voted 26 to 24 last week to approve the proposal, with 25 of the chamber's 30 Democrats voting in favor. A Republican provided the one-vote margin needed to put the measure over in the 50 member Senate.

At least 102 votes are needed to approve the measure in the House, where Democrats hold 116 of 203 stars. So far, however, Democrats could count only 99 House votes in favor of the budget. The plan has been staunchly opposed by upstate Democrats and a solid Republican caucus who claim that it is "phony."

Republican Minority Leader Robert J. Butera said that the Democrats' proposal is "simply a spend now, tax later" budget plan. He said the decision puts off until the fall a necessary $300 million tax increase to fund those institutions left out of the Democratic budget plan.

Butera, a Republican who has announced his candidacy for the 1978 gubernatorial race, said he is "baffled" by the predicament in which the state finds itself.

"Last year we started with a $108 million surplus. We collected revenues last year at the highest rate in a decade," he contended. "But now we have ended up with a $156 million deficit and we are being asked to use this year's tax dollars to fund last year's bills, instead of using this year's tax dollars to fund this year's needs . . . unbelievable."

Butera acknowledged that both republicans and Democrats in the legislature are reluctant, for political reasons, to approve a budget that would call for new taxes now or in the future. But he said they would be less reluctant to vote for new taxes if the state had spent wisely in the past.

The last time the legislature voted for a tax increase was in 1971. But Butera claims that Pennsylvanians have been getting "invisible tax increases" since then because of inflation.

The republican leader offered a counterplan he said would do nearly everything the Democrats want done except raise taxes. A key provision of it calls for a $156 million loan to payoff last fiscal year's deficit. The state would borrow the money from the $5 billion state and school employees retirement system or through bonds.

The House was expected to meet tonight to consider the Republican plan. However, neither Democrats nor Republicans were optimistic.

Meanwhile, nearly 800,000 welfare recipients and 108,000 state employees go without money. As of today, 276,954 welfare recipients had missed $33 million in relief checks since Aug. 1 and more than 91,000 state employees were owed $50.4 million in back pay. State contractors were left with $22.9 million in overdue bills.