Northern Virginia Rep. Stanford E. Parris celebrated his birthday with Vice President George Bush last night at a fund-raiser that netted $50,000 -- a quarter as much as Parris' Democratic opponent has raised in his entire campaign.

Bush came to suburban Springfield to tell more than 100 builders, lawyers, lobbyists and others that the Reagan administration solidly supports Parris' reelection bid despite the congressman's vote a few hours earlier to override a presidential veto on a spending bill.

"We do not look for total rubber stamp uniformity, and if we did we wouldn't find it here," Bush said as a beaming Parris stood by. "He represents this district just exactly as it should be represented, with integrity and honor."

About 30 couples paid $1,000 to mingle with Parris and Bush for half an hour in a cocktail reception, and another 100 couples paid $250 to hear a brief vice presidential speech and watch Bush help cut a cake for Parris' 53rd birthday. Herbert E. Harris, the former Democratic congressman who is running against Parris to try to win back his seat, told a reporter by telephone earlier that the birthday party would prove once again that Parris is the candidate of the rich.

"Stan can have the Rolls-Royce crowd," said Harris, who unseated Parris in 1974 and then lost to him in the Reagan landslide two years ago. "I'm quite comfortable with the people who drive the Plymouths, the Fords and the Chevys."

"Is that why he voted $1.2 billion for Chrysler," Parris retorted last night after he was told of Harris' comments.

Partygoers included car dealer Ted Britt, builders Herbert Aman and William T. Hazel, developer Milton Peterson and lawyer-lobbyist former Watergate minority counsel Fred D. Thompson.

They helped push the Parris campaign treasury to $400,000, two-thirds of the campaign's $600,000 goal. Harris said yesterday that he had raised about $200,000, or half his campaign target.

Parris' successful fund-raising this week allowed him to launch an expensive radio advertising campaign that hammers at Harris as being "full of hot air." Harris said he had not set a date to begin his media campaign.

Parris, a cheerleader for Reaganomics last year, deserted the president this summer on two key bills -- the tax increase approved last month and the veto override yesterday, on which 81 GOP congressmen joined the Democratic majority to deal the president a major defeat.

Parris' campaign manager said those votes would not dampen administration support.

"They're realistic," Fred Allen said. "They know we have to stay alive and they know we've been with them 85 or 90 percent of the time."