Newly elected Prince George's County Executive Parris Glendening said yesterday that as many as 600 county employes could be laid off next year if county officials are unable to find new sources of revenue to offset an anticipated shortfall of more than $30 million.

"If we don't have revenue then we're going to be cut," said Glendening, a Democrat who won his county executive seat by a landslide last week. "There's no way of finessing it, there's no way of being polite about it, there's no way of being nice about it."

Glendening replaces Republican Lawrence J. Hogan Dec. 6 as the chief executive of a county that employs about 14,000 people, including school personnel, on a $560 million operating budget. He inherited a government still reeling from cutbacks and the layoffs of 507 teachers this year that were due in part to the county's property tax ceiling, TRIM. One of the most restrictive ceilings in the country, TRIM limits the county to collecting no more in property tax than it collected in fiscal 1979, which was $143 million.

A referendum -- which Glendening supported -- to lift slightly the ceiling was defeated by county voters last week, leaving the executive with few alternatives other than finding additional money or cutting personnel.

County employes will have to share the layoff burden with school employes next year, Glendening said.

"The absolute minimum is that we're over $32 million short, and I'd say realistically, between $32 and $38 million short," Glendening said. "I think everyone knows that as well as I do."

Glendening based his remarks on last year's $561 million operating budget, and a 10 percent inflation rate. "We'd need $56 million just to stand still," he said.

He said he expects the county will receive about $20 million extra revenue from "normal growth" in state aid and increases in other revenues such as transfer taxes, leaving the county with $36 million less than it needs simply to maintain current services.

. Glendening's job is made no easier by the fact that all the county's major labor unions start negotiating new contracts this year. Labor leaders yesterday said they were not surprised by the executive's comments.

"I see massive layoffs and I don't see any white knights coming to save us," said Karen Kuker-Kihl, a lobbyist for the National Education Association and a director of the Maryland State Teachers Association. "You cannot pay for things without money and I cannot understand why people are shocked by this."

Mahlron Curran, president of the county's Fraternal Order of Police chapter, said Glendening told him in a meeting last week that layoffs might be possible, "within the rank and file of police."

Glendening made his remarks at his first press conference held to announce the formation of eight citizen "task forces" he created to help him review county policy.

He repeated his pledge to work with the county's state legislators for an increase in state aid. Though he declined to name any specific proposals, saying he wanted to allow his study groups the freedom to think creatively, he said he would consider efforts to increase some users' fees, to restructure state aid formulas, and to establish some type of local tax. Neverthless, legislators reiterated their belief that little, if any, additional state aid would be forthcoming.

Del. Gerard Devlin, vice chairman of the House Ways and Means Committee, which reviews all tax bills, said some increased help might be possible if there were growth in the state's sales tax and income tax, "but the economy's flat and unemployment is at an unusually high level for Maryland, 8 percent."

Del. Timothy Maloney, a member of the Appropriations Committee, pointed out that Maryland lost $112 million in federal aid last year. Few legislators will be willing to increase taxes, said Sen. Thomas V. (Mike) Miller, president of the county's Senate delegation. Miller recommended the county abolish some departments such as the Consumer Protection Commission, the Commission for Women, and the Human Relations Commission, saying these agencies duplicate state-run departments.