The Senate Armed Services Committee yesterday recommended spending $157 billion on defense in 1981, $6.5 billion more than President Carter wants, and the Senate Budget Committee last night approved a $156.3 billion defense total.

Such a large increase for the Pentagon could throw the whole congressional budget-writing process into turmoil.

Goaded by President Carter, Congress now is bent on balancing next year's budget, partly through higher taxes and domestic spending cuts, with defense left untouched. Congressional liberals have gone along so far, but a further Pentagon increase may move them to rebel.

The Armed Services Committee proposed its figure in a two-paragraph report to the Budget Committee and gave no details of what the added money was intended to provide. Defense spending this year is expected to reach $134 billion.

Budget Committee Chairman Edmund S. Muskie (D-Maine) had suggested a defense figure of $148.8 billion as part of a total $610.8 billion budget a few hundred million less than Carter's recommended total.

But a proposal by Sens. Ernest F. Hollings (D-S.C.) and Peter Domenici (R-N.M.) to peg the number at $156.3 billion passed 10 to 8. Much of the 1981 increase in the proposal would be earmarked for higher military pay.

To help the all-volunteer services retain experienced personnel, the two senators want an 11.7 percent "full comparability" pay raise next fall instead of the 7.4 percent increase in Carter's budget. Also, they want the Defense Department to be required to absorb only 20 percent of the increased pay costs through other program reductions instead of the 40 percent Carter proposed.

Hollings told the Budget Committee the Pentagon was having great difficulty retaining experienced personnel, especially what he called "middle-level technicians" and pilots. The Air Force, he said, will be shy at least 3,500 pilots next year.

Domenici argued that federal spending on health, housing, welfare and other programs has been rising swiftly in recent years after adjustment for inflation while defense outlays have been flat.

"We have $82 billion in new revenue [for fiscal 1981] that we did not have this year. If this is not the year to increase defense spending . . . when can we?" Domenici asked.

The Armed Services Committee recommendation, approved 13 to 2, included money for taking battleships out of mothballs, purchases of several new ships and aircraft, as well as allowances for higher pay, sources said.

The committee asked the chief of staff of each service a few days ago to tell it how they would spend $10 billion more than Carter recommended if they had it. The chiefs were also asked how much more they thought they would need to carry out the commitments Carter has made recently, particularly in the Middle East and Persian Gulf.

The chiefs met with the committee twice, including once this week, to give their answers. Sen. Gary Hart (D-Colo.), who voted for the higher spending figure, said this "happens every year." But Hart said he feels the chiefs are "responsible people who are not backdooring their commander-in-chief."

"They always have a shopping list," Hart said, "and they never get all they want" from the president.

The Hollings-Domenici proposal to the Budget Committee included provision for 41 additional aircraft and two attack submarines for the Navy, more ammunition, missiles and helicopters for for the Army, a new manned bomber, more military scientific research and added funds for training, flying hours and steaming time for ships.

The two senators also proposed substantially higher defense spending for the 1982-1985 period. All together, for the next five years, they want to spend more than $100 billion above what President Carter has projected.

Unless offsetting cuts were made in non-defense programs, the Hollings-Domenici proposal would absorb more than half of a "surplus" the Budget Committee has estimated would otherwise be available for eventual tax reductions.

Hart, for one, said such a massive increase in defense spending for future years would not be approved "without a serious national debate" about not just the quantity of defense outlays but also their quality.

Given the tightness of the $610.8 billion total spending figure targeted by Muskie, committee sources said any large increase in defense spending would not be offset by large cuts elsewhere. In order to keep the budget balanced, they said, the $16.3 billion the committee set aside Monday for a 1981 tax cut likely will have to be reduced.

The House Budget Committee earlier proposed $147.9 billion in defense spending as part of its budget resolution. That resolution, pending before the House Rules Committee, will be voted on by the full House after next week's Easter Recess.