Two conservative GOP senators urged President Reagan yesterday to sign legislation offering relief for the long-suffering housing industry, but administration officials said afterward that Reagan will veto the bill as promised.

Sens. Richard Lugar (Ind.) and Jake Garn (Utah) said they argued in a half-hour meeting with Reagan that the legislation was needed as an anti-recession stimulus to provide jobs and to help pull the real-estate industry out of a four-year slump.

But officials said Reagan shares the view of his principal economic advisers that to sign the housing aid bill would be to open the floodgates to multimillion-dollar bailouts for agriculture, small business, autos, savings and loans and other industries hurt by the recession.

But there were dissenting opinions in the White House, especially among political aides who have been impressed by the wide bipartisan support the housing aid measure enjoys in Congress and who are concerned about the effect of high unemployment and interest rates on GOP candidates this fall.

The housing relief measure, a rider on the 1982 Urgent Supplemental Appropriation bill, would commit $500 million a year in federal dollars for up to five years to subsidize mortgage interest rates up to 4 percent for moderate-income families. The subsidy would have to be paid back eventually, and in no case would a homebuyer's interest rate be lower than 11 percent.

Lugar argued that the bill would provide time for Reagan's overall economic program to work without interfering with it. The senator, running for reelection in economically depressed Indiana, said he noted during the meeting with Reagan that the legislation would create jobs this fall.

Just how many jobs is a matter on which Lugar and the administration disagree. Lugar estimates the bill would spur the construction of 250,000 homes nationwide and create more than 500,000 jobs. Budget director David A. Stockman argues that it would increase national employment by 0.1 percent "at best" and would mean building only about 31,500 homes.

The National Association of Homebuilders strongly supported the legislation but the measure has been greeted with something approaching indifference by realtors, mortgage bankers and thrift institutions. The reason for that is the legislation would aid in the construction of new housing but would not help realtors, for example, who have an oversupply of existing houses.

Another measure tacked on to the supplemental bill would repeal a generous, $75-a-day tax deduction that members of Congress gave themselves last fall. In deliberations over that provision yesterday, House members attempted to get the Senate to agree to limit outside earned income to 30 percent of their annual congressional salary. The House already has such a limit.

The Senate rejected the proposal, 54 to 41, and sent the bill back to the House, where it is likely to be voted on again today. If the House persists, the proposal will go to another joint conference committee.