Vice President Mondale yesterday announced an administration proposal that would pay people to adopt hard-to-place foster children and would expand current federal child welfare services.

Health, Education and Welfare Secretary Joseph A. Califano Jr. characterized the program as Carter's "pro-family" reform of a "viciously anti-family" child welfare system. He testified yesterday on the proposal before the Senate Finance Subcommittee on Public Assistance headed by Sen. Daniel Patrick Moynihan (D-N.Y.).

The proposal has two major parts:

Currently, the federal government spends $171 million to help support 117,000 children in foster care. But no money is provided if a child is adopted. The proposal would allow those foster care funds to go to adoption subsidies for low- or moderate-income families wishing to adopt so-called "hard to place" foster children - older, physcially or mentally handicn estimated $2,000 would go to the adopting family annually until the child reached 18 if the family income stayed below an as yet unspecified level.

In addition, some Medicaid funds that are cut off it foster children are adopted would be continued.

Second, the proposal would provide an additional $209.5 million by the mid-1980s to expand state child welfare services. The first $63 million would be granted next fiscal year to develop programs for reviewing foster care cases, promoting adoption or unifying children with their natural parents when feasible, and providing family drug and alchol and martial social services.

Once states set up these new programs and comply with "broad restrictions" to be set by HEW, the rest of the money would be phased in, Califano said the restrictions on the use of the money would not be rigid - "we don't want to cross every T and dot every I" - as he was questioned repeatedly by senators on the subcommittee who felt there should be no federal restrictions in order for states to get the money.

The administration proposal presents a turnabout from three months ago when officials opposed similar congressional adopting proposals on the basis that they would cost too much.

"But that was early in the administration - and OMB (Office of Management and Budget) thought they were still working for Ford," Califano joked yesterday.

There are three basic reasons for the change. One, the administration wanted to influence legislation, and an adoption bill passed the House by a wide margin in June and looked as if it would have a good chance of passing.Second, Mondale's long advocacy of such a plan masked with President Carter's professed concern for the family. Third, the controversy over the administration's support of cutting Medicaid funds for abortion made it expedient to present an "alternative to abortions."

Califano yesterday played up the proposal as a "pro-family move," but also said "you could certainly say it presents a alternative to abortion. Pro-choice forces who turned out for his testimony were not to sure, pointing out that the proposal says nothing about subsidizing people to adopt healthy, young babies.

Although there was no indication in either the proposal or Califano's testimony, in response to a question the HEW Secretary said that the administration plan "would absolutely pick up" part of a Senate adoption bill that provides a guarantee of medical expenses for pregnant women who agree to put their babies up for adoption after birth. "That absolutely would be in this proposal - I just haven't described it in all the detail," said Califano. But a White House aide said later that this was not part of the Carter plan.

Sen. Alan Cranston (D-Calif.) sponsor of that original bill, said he would introduce new legislation worked out with the White House next week.With the administration's backing, he predicted, a bill would be enacted this year.

How much the House-passed bill will be factored into the senate bill remains unclear. For one thing, the House Bill differs from the administration proposal in that there is no restriction on the adopting family's income. It also provides separate health funding rather than Medicaid for adopted children, and sets far more rigid restrictions on the states to find suitable homes for children or reunite them with their families.