The Children's Defense Fund said yesterday that Reagan administration proposals enacted in 1981-82 or proposed in the current budget will slash fiscal 1984 federal spending on poor and crippled children and their families $12.5 billion from what it would have been under previous law.

"They are misleading the American public about the real impact of the cuts on the poor and on American children," CDF director Marian Wright Edelman told reporters in releasing a 244-page study of budget cuts.

She said President Reagan and Office of Management and Budget Director David A. Stockman were trying to convince the public that the administration is only cutting the rate of increase of programs targeted toward the needy, not actual program levels, and that the "social safety net" is still in place. Both assertions are untrue, she said.

"Without Reagan administration changes in program levels and eligibility, voted in 1981-82 and proposed for this session, federal budget authority for 20 key poor-people and children's programs would have been $67.4 billion in fiscal 1984, but if he gets what he wants, it will be only $54.95 billion," Edelman said.

Of the $12.5 billion reduction, $9 billion is the result of 1981-82 proposals already passed by Congress. Proposals in Reagan's current budget account for the remaining $3.5 billion.

Edelman said that a "children's survival bill" adding to children's programs and cutting "waste and abuse" in departments or increasing taxes on luxury items would be introduced in Congress.

The 20 programs do not include subsidized housing for the poor, Medicare or Social Security. They do consist of Aid to Families with Dependent Children, Medicaid, food stamps, child nutrition, foster care, adoption assistance, Title I compensatory education, education for the handicapped, maternal and child health, mental health, child welfare, child abuse, social and community services grants, juvenile justice, runaway youth programs, Head Start, youth employment, legal services, supplemental food for women, infants and children and energy assistance.

The report said that that many programs such as AFDC, food stamps, higher education, child nutrition and low-income energy aid would suffer absolute reductions from fiscal 1983 to 1984.