The House voted overwhelmingly yesterday against President Reagan's proposed sale of sophisticated radar planes and other aircraft equipment to Saudi Arabia, while the White House continued its uphill lobbying campaign to ward off a vote in the Senate that would kill the $8.5 billion deal.

By a margin of 301 to 111, the Democratic-controlled House adop- ted a resolution to disapprove the sale of Airborne Warning and Control System (AWACS) planes and other items in the biggest arms sale in history.

Despite Reagan's contention that the deal is crucial to the success of his Middle East policy, 108 Republicans voted for the resolution.

"Well, that was expected," the president said after the vote. But he also noted that a congressional veto of the sale must be approved by both houses, and he restated his determination to persuade a majority of senators not to follow the House lead when they consider the disapproval resolution.

In an apparent attempt to give the president more time, the office of Senate Majority Leader Howard H. Baker Jr. (R-Tenn.) announced late yesterday that the Senate vote on the resolution will be postponed from next Tuesday, as originally scheduled, until sometime the following week.

An aide to Baker said the vote is being deferred because Reagan is to be in Mexico at an economic summit meeting next week. The president is expected to meet in Mexico with Prince Fahd, head of the Saudi government, and there has been speculation that the two might agree on an announcement or another move that could influence the Senate vote.

"I have to go back to work, and what I have to go back to work on is AWACS," Reagan said as he left a ceremony in the White House Rose Garden.

During the day, several senators paraded through the White House to hear the president's arguments, but the net effect appeared to indicate that Reagan has a long way to go to reverse the apparent majority against the sale.

Reagan's efforts brought three more Republican senators into open support of the sale: Ted Stevens of Alaska, Mack Mattingly of Georgia and Dan Quayle of Indiana. All had expressed reservations about terms of the Saudi deal, but leaders of the Senate opposition to the sale had expected them to back the president in a showdown.

Reagan was less successful in his attempt to win over three others more outspoken in their opposition: William S. Cohen (R-Maine) and David H. Pryor (D-Ark.), co-sponsors of the Senate disapproval resolution, and Ernest F. Hollings (D-S.C.).

After talking with the president, all three said they were willing to keep an open mind, but had not heard arguments that could overcome their concern about the administration's arrangement with the Saudis.

They said they fear that it does not contain sufficient safeguards to prevent the equipment from being used against Israel or falling into the hands of U.S. foes.

The administration's latest attempt to assuage Senate anxieties about control of the equipment centers on a letter, being drafted at the White House, that will address questions of security, maintenance and control of the AWACS planes and offer written assurances by Reagan on these points.

Quayle and Mattingly said their decision to support the sale was made after seeing an outline of the proposed letter. However, two members of the Senate Foreign Relations Committee, which is scheduled to vote on the disapproval resolution today, said the letter will not be enough to tip the AWACS battle in the president's favor.

Sen. Richard G. Lugar (R-Ind.), a proponent of the sale, said, "It will be a help, but it won't turn it around." Sen. John Glenn (D-Ohio), a leading opponent, insisted that 53 to 57 senators are against the deal. Both appeared on NBC's "Today" show.

Reagan also collected public promises of support yesterday from Sens. John P. East (R-N.C.) and James Abdnor (R-S.D.), who were expected to vote for the sale. Sen. Walter D. Huddleston (D-Ky.) also talked with Reagan yesterday, but said he remains uncommitted.

According to nose-counters on Capitol Hill, the net effect of the White House lobbying appears to give the administration between 30 and 40 Senate supporters, while more than 50 seem inclined to vote against him.

That does not represent any significant change from predictions made by opponents of the sale when the AWACS battle began in earnest last month.

An aide to Sen. Dennis DeConcini (D-Ariz.) said yesterday that someone with "a very close relationship with the White House" had told DeConcini that Reagan probably would not campaign against him next year if he changes his opposition to the sale. The report subsequently was denied by White House deputy press secretary Larry Speakes.

Amid the jockeying for Senate votes, arguments for and against the sale were rehashed during four hours of debate preceding the House vote. Opponents reiterated concern about lack of U.S. control over the equipment and possible dangers to Israel, while Reagan's supporters vainly sought to portray the sale as vital to U.S. Mideast interests and the president's ability to conduct foreign policy effectively.

In the vote, the president found his supporters outnumbered almost 3 to 1, with the bulk of his votes from southern states and a scattering of Republican redoubts in the Midwest and Rocky Mountain regions.

All seven members of the Maryland delegation voted for the resolution of disapproval. Virginia Republicans Frank R. Wolf and Stanford E. Parris split, with Parris voting against.

In addition to five AWACS planes, the proposed sale includes eight aerial refueling tankers, air-to-air Sidewinder missiles and range-enhancing fuel tanks for the 62 F15 jet fighter-bombers that the United States agreed to sell to Saudi Arabia in 1978.

Sen. Charles H. Percy (R-Ill.), chairman of the Foreign Relations Committee, yesterday raised the possibility that Reagan could use his executive powers to go ahead with the sale even if Congress vetoes it.