The energy and economic policies of the federal government could threatened Virginia's continuing prosperity, several state leaderes said here yesterday.

Hammering at familiar themes for Virginians, J. Marshall Coleman, the state's attorney general, said the nation's economic woes are primarily the result of too much federal government spending and regulatory excesses.

"It's the government's influence on the economy that has so plainly gone awry," Coleman said at a conference on the state's economic picture held at James Madison University.

Zack C. Dameron Jr., president of the Virginia Manufacturers' Association, said federal energy and environmental policy threatens to result in serious energy problems throughout the state.

"The ineffectiveness of present and past administrations and Congresses to deal adequately with energy policies" threatens the "vitality of the state's economy," Dameron said.

Further, Dameron labeled Carter's windfall profits tax on oil companies "misnamed and misguided" and said passage of the pending legislation would "reduce the incentives for private industry to develop new energy sources."

Virginia, he said, could solve most of its energy needs if the federal government would loosen enveronmental standards that set limits on coal-fired plants.

"Unduly restrictive environmental policies are a major deterrent to the state's usage of all its fossil fuels," he said, calling the Clean Air Act "disastrous for this country."

The one-day conference, jointly sponsored by Valley of Virginia Bankshares Inc. and James Madison University, brought about 200 state business representatives here in an effort to assess the state's economic picture.

But with unemployment currently at a rate of only 4.5 percent and continuing successful efforts by the state government to attract new business ventures to Virginia, the session primarily focused on the national economic picture and its effects here.

However, Dr. Carl Weaver, an associate finance professor here, predicted that state businesses should plan on significant utility rate increases during 1980. Virginia Electric and Power Company, he said, is likely to seek a 10 percent rate increase next year.

Nevertheless, Coleman in particular emphasized his government to challenging the federal role in Virginia affairs. "States can be the masters of their own destinies," he said.

States must develop a new approach to challenge regulatory overload and meaningful programs for decentralization of government services, he said.

James Parthemos, senior vice president and director of research for the Federal Reserve Bank of Richmond, offered one of the few notes of economic optimism concerning government policy.

Noting the Fed's action to raise the prime rates, Parthemos said interest rates would not continue to go up much longer.

"The slowing in credit demand should bring down interest rates next year, he said.