President Carter's fiscal 1978 budget was analyzed and found wanting yesterday by tha nation's big city mayors, who said it contained too much for defense and not enough for solving curb an problems.

The criticisms were contained in at 57-page report by the U.S. Conference of Mayors that said the Carter budget fell $10 billion short of what was needed in domestic spending while increasing the defense budget by $11.7 billion over fiscal 1977. Widely publicized reductions in the defense budget were misleading, said conference director John Gunther, because they were reductions in increases asked by President Ford, not in the actual budget.

The tone both of the report and of Gunther's press conference was that much had been expected from the advent of a Democratic administration and little had been delivered by the Carter budget.

"With Ford we had little hope," said Gunther. "With Carter we had much hope. Our hopes were beyond practicality and reality. We should have known better."

The mayors were particularly disappointed with what they called a lack of balance in Carter's economic package, saying it was weighted too heavily toward tax reduction and insufficiently toward spending.

The analysis also complained that Carter had omitted three programs of high priority to the mayor- national health insurance,welfare reform and an urban development bank that would stimulate private investments in deterioriating cities.

"Despite a few significant program gains, the relief which the cities expected from President Carter is still more promise than reality," the analysis said. "In many budget areas, important urban programs have been cut below 1977 levels or their growth restrained to rates of increase well below inflation rates."

But this has not been true of degense spending, the mayors observed, saying that President Ford established a trend of defense budget increases in excess of inflation that started in fiscal 1976 and continues.

"The Carter budget does not include any significant deviations from the earlier Ford program," said the mayors' report. "The bulk of the budget cuts consist of deferrals, delays or reallocations for spending of weapons, rather than actually terminating many major systems. There is no change in the force structure."

The mayors were not entirely critical of the Carter budget. They complimented Carter for increasing funds in the community development block grant program, which helped the cities avoid a potentially divisive fight among themselves on who should get the limited funds previously available.

Gunther said his organization would continue to press Congress for increases in the budget levels proposed by the administration.