The Prince George's County Council reversed itself yesterday and voted to sustain County Executive Parris Glendening's veto of a bill that would have established a system of criminal checks for employes in child day-care centers.

The 6-3 vote against overriding the executive veto came just over a month after the council voted 8-to-1 to approve the bill introduced by member James M. Herl. A veto stands unless two thirds of the nine-member vote to override.

The five council members who changed their minds on the legislation passed in November each said that they had had problems with the bill all along.

"This legislation was passed with the full knowledge of everybody that it was going to be a shelf piece of legislation," said Jo Ann T. Bell, who added that it was never fully decided who would fund or staff the operation.

"I voted for it tongue in cheek," said Frank P. Casula of his original vote in favor of Herl's bill.

Glendening vetoed the bill on Dec. 18, calling it "faulty." He said it failed to cover many day-care workers and contained no funding provision to pay for its administration and enforcement.

The state, he said, is also poised to enact a more comprehensive version of the same legislation this year.

Herl, in a three-page memo handed to council members before the vote, argued that the council should override Glendening's veto so that Prince George's could send the "right message" on child abuse prevention to the rest of the state.

"In this instance," Herl wrote, "the choice exists (between) the right of government to protect the health and welfare of children in day-care centers" and the right of day-care workers to be free from harassment.

The screening, he noted, would prevent centers from hiring adults with "convictions for child abuse, sexual offenses or crimes of violence."

The county, he said, should not await state enactment of screening legislation.

A draft proposal is now being reviewed by Gov. Harry R. Hughes for introduction into the 1985 General Assembly.

Council member Floyd Wilson, the only member to vote against the bill in November, said it would make no sense for the council to knowingly pass a bill that is defective, even if well-intentioned.

"I don't know what more you want other than to simply put on a show," Wilson said. "Look at what it's going to cost you. No one knows where the money is coming from."

County health officer Helen B. McAllister has said that implementation of the bill in its final form would have cost nearly $277,000 the first year and more than $167,000 each subsequent year.

The police department, which had originally been designated to perform the background checks, told the council it would have cost $1.2 million to run the program.

Sue V. Mills, who along with Herl and Anthony Cicoria voted to override Glendening, said that yesterday's council action was a sign of weakness.

"I find it a little amazing that one executive veto and everybody heads for the hills," she said.