Prince George's County Executive Parris Glendening unveiled a $669 million budget yesterday for the next fiscal year, saying the county is finally able to expand its programs, adequately reward its employes and fund major new education initiatives after years of austerity.

The budget, the largest ever proposed, is slightly more than 10 percent bigger than last year's but, because of $31.8 million in increased revenue from increased house sales and construction and other development, it will require no new taxes to fund, Glendening said.

Nearing the end of his first term, Glendening said that the new budget is "a source of excitement and pride and signals the beginning of a new era" for the county.

The rosy picture painted by Glendening is similar to that shown in other jurisdictions locally and nationwide, said Philip Dearborn, vice president of the nonprofit Greater Washington Research Center.

In the early 1980s, Dearborn said, "Things were pretty grim for local governments. The economy wasn't growing, we were coming out of a period of high inflation and high interest rates, and there was the recession."

This period, he said, was generally one of belt-tightening by local governments -- especially Prince George's, where TRIM, a voter-imposed property tax revenue cap, was in force. That limit was modified by county voters in 1984 to allow the county to receive added revenue from new development and increased assessments.

"All the local governments are doing very well right now. It's a pattern prevalent across the country," Dearborn said.

As a result, the property tax rate in Prince George's will remain at $2.40 per $100 of assessed value, though homeowners' taxes will go up as their property values increase, thereby increasing total county revenues.

Glendening said there has been substantial new economic development in the county of 662,000, the largest in the metropolitan area.

"There is no bad news today," he said at a morning news conference. The budget was immediately sent to the County Council, which must act on it by June 1 and is expected to approve it with few if any changes.

In his first year in office, Glendening said, the county faced an "extreme crisis . . . large deficits . . . a great deal of uncertainty." County employes accepted wage freezes. In the next two years, he said, budgets were tight but there were "minor enhancements" in services.

Now, Glendening said, thanks to the TRIM change, the development boom and increased state aid, he can propose new and expanded programs despite a $12 million reduction in federal revenue sharing funds.

The new programs include an already announced increase of $40 million for education, said to be the largest increase ever for Prince George's schools. Of that, $16 million comes from special taxes levied on developers in some areas of the county, $11 million from additional state aid and the rest from increased property tax revenues.

The money is to be used to fund an expanded magnet schools program, increase starting teacher salaries from $15,700 to $19,000, buy additional textbooks and materials and decrease class sizes.

The budget also calls for the hiring of 65 more law enforcement and public safety employes, 11 more public nurses and 12 more environmental workers.

In addition, Glendening said, the budget includes funds to open a new library in District Heights and a senior day-care center in Laurel. The budget also would pay for improved roads and other capital projects, should the voters approve a proposed $117 million bond issue.

It also contains money to fund pay raises in eight county labor contracts, with increases in the forthcoming fiscal year ranging from 2 percent to 6 percent, and a 6 percent raise for nonunion employes.

Valerie Preston, executive director of the 5,300-member Prince George's County Educators' Association, said that labor-management relations are "better than in the past." Her union recently reached a tentative agreement on a three-year contract calling for yearly raises of 6 percent, 8 to 9 percent and 7 percent respectively.

She said Glendening was "moving in the right direction" with funding to raise pay and improve programs.

"There is a degree of labor peace and stability unrealized for quite a number of years in Prince George's County," Glendening said. "I'm pleased to give our employes a much deserved and long-delayed adjustment."

Although he has not yet formally announced his intention to seek a second term, Glendening told reporters, "I anticipate being here for subsequent budgets."

Over the next four years, he said, he foresees " . . . a period of continuity and growth."

Yesterday, Glendening's predecessor recalled tougher times. Said Lawrence W. Hogan, county executive from 1978 to 1982, "Interest rates were so damned high then. We paid more for bond issues, for gas." Consequently, he said, his administration cut staff and the amount of rented space.