Congress is closing the books on four years of President Reagan's domestic belt tightening with pre-election spending spurts in health, education and welfare programs that Reagan had set out to trim.

A House-Senate conference committee agreed this week to raise the ceiling on Pell Grants for low-income college students from $1,900 to $2,100, adding $525 million to a program Reagan had sought to squeeze.

The college aid increase was symptomatic of others tucked into the big spending bill for the Labor, Education and Health and Human Services departments that was approved as Congress neared adjournment and final passage of a catchall spending bill for the fiscal year that began Monday.

For all the posturing in the past few years about fiscal austerity, Congress once again showed an inclination to support selected increases in health, education and welfare programs -- despite Reagan's protests.

Overall, Congress appears to be sticking within the domestic discretionary spending limits negotiated with the White House last spring, so Reagan is not likely to exercise his veto because of "budget-busting" in these programs. But within those limits, election-bound lawmakers nibbled away at Reagan's sweeping early budget cuts.

Reagan tried to eliminate the community services block grant -- anti-poverty programs that once were part of the old Office of Economic Opportunity and Community Services Administration -- but Congress approved $374 million for the program.

Reagan tried to eliminate the work incentives program, designed to help welfare recipients get training and work experience, but Congress approved $270 million.

Reagan sought $115 million to train health professionals, but Congress approved $234.5 million, nearly twice that amount. The funds included a big boost for nursing programs, including fellowships and research grants, for which Reagan sought $14 million and Congress approved $66.7 million.

In a small but symbolic shift, Congress also approved an amendment that would restore the basis of food stamp benefits from 99 percent to 100 percent of the Agriculture Department's nutritionally adequate low-cost diet plan known as the "Thrifty Food Plan." This move would add $137 million to the cost of the food stamp program.

Congress has been resisting Reagan's cuts in social programs since the deep recession of 1981-82. The administration's internal budget studies, as well as those published by Congress, have shown that Reagan made the most progress in domestic spending cuts in his first year and substantially less since then.

One reason is the rise of the "fairness issue" -- the charge that Reagan's policies unfairly hurt the poor while helping the wealthy. The issue inhibited the administration effort to cut further into programs for the poor and middle class.

But Office of Management and Budget Director David A. Stockman predicted earlier this year that Reagan's second-term agenda would include a renewed effort to trim programs such as student aid, farm price supports, Medicare, veterans programs and federal civilian pensions.

Whether Congress will be willing to take the budget knife to these and other domestic programs in 1985 may depend largely on the outcome of the election. An increase in the Republicans' strength on Capitol Hill could result in a vigorous new White House effort to cut spending.

But, for now, even Reagan's allies in the Republican-controlled Senate seem inclined to go no deeper.

When the big Labor-HHS appropriations bill came to the Senate floor, there were no amendments seeking cuts -- only increases. And when the Senate took up last spring's "Rose Garden" budget compromise with the White House, it added $2.7 billion for health care, education and biomedical research at the behest of some GOP moderates.

These priorities are reflected in the spending bills approved in Congress' final hours. In addition to the Pell Grant raises, Congress increased a block grant for maternal and child health care from $399 million last year to $478 million.

Congress also approved sizable increases in funding for the National Institutes of Health, where the administration had sought to hold the line.