Northern Virginia Rep. Stanford E. Parris spent about $700,000 to win reelection this year, helping to make his 8th District contest against former Democratic representative Herbert E. Harris II Virginia's first $1 million congressional race.

Harris raised $384,000, almost twice as much as he spent while losing the seat to Parris in 1980. Both candidates raised more than $50,000 from political action committees (PACs) in the period after Oct. 14 alone, as contributors rallied for what most polls showed would be a close race. Parris, the state's biggest spender in a House race, won by about 1,500 votes, a 1 percent margin, in the district that includes Alexandria and portions of Fairfax, Prince William and Stafford counties.

Throughout the Washington area, U.S. Senate and House incumbents outspent their rivals, in several cases by overwhelming margins, according to reports that had to be filed by yesterday with the Federal Election Commission. In the race for the Senate seat vacated by retiring Virginia independent Sen. Harry F. Byrd Jr., Republican winner Paul S. Trible Jr. outspent Democratic Lt. Gov. Richard J. Davis by $2 million to $1.1 million.

Maryland Democratic Sen. Paul S. Sarbanes spent more than $1.5 million -- a record for the state -- defending his seat against challenger Lawrence J. Hogan, the Republican Prince George's County executive whose campaign was consistently plagued by lack of funds. Hogan had raised about $425,000 in contributions, plus $235,000 from the National Republican Senatorial Committee, as of Oct. 13, though Hogan's latest FEC report was unavailable yesterday.

Sarbanes was also fighting a battle against the National Conservative Political Action Committee (NCPAC), which made him its number one target in 1982 and spent $625,000 to defeat him. The attack, however, benefited Sarbanes' fund-raising, helping him to raise thousands from out-of-state liberals and more than $250,000 from labor PACs.

In outspending Democrat Davis by nearly a 2-to-1 margin, Republican Trible was aided by $640,000 in PAC contributions, most of which came from trade associations and business, particularly defense contractors and oil and gas interests. He also received a spate of last-minute contributions from conservative groups like Congress of Conservative Contributors, the National Coalition for a Free Cuba, the Pro-Life Congress and the Fund for a Conservative Majority.

Davis, on the other hand, received only $236,000 in PAC contributions, mostly from labor groups. Robert Watson, one of his top aides, today blamed Davis' narrow loss on Trible's huge spending advantage. "You give me another million dollars and I'll give you another 34,000 votes," he said.

In the two Maryland congressional races, incumbent Democrats far outdistanced their opponents in fund-raising. Rep. Michael D. Barnes raised about $260,000 for the campaign against Republican Elizabeth Spencer, who spent $28,000 of which $20,000 was lent by Spencer. Rep. Steny H. Hoyer raised $220,000 in his contest against a political unknown, William P. Guthrie, who did not file an FEC report. No report is necessary for candidates who raise less than $5,000.

Parris' Republican colleague from Northern Virginia, Rep. Frank R. Wolf, outspent Democratic challenger Ira M. Lechner $503,000 to $389,000. Lechner lent his campaign $55,000, which he raised by mortgaging his Arlington home, and his campaign remains $66,000 in debt, according to the report filed yesterday.

Virginia's second biggest spender in a House race appeared to be Democrat Norman Sisisky, who spent $519,000 to unseat GOP Rep. Robert W. Daniel in southern Virginia's 4th District. Sisisky, a soft-drink magnate, lent $349,000 of his own money to the campaign.

Parris raised money in the final period, as he had throughout the campaign, from Northern Virginia builders, lawyers and car dealers and from executives of Richmond's Main Street business establishment. Former highway commissioner William B. Wrench, a Republican appointee, and current Virginia highway commissioner Joseph M. Guiffre, an appointee of Democratic Gov. Charles S. Robb, both contributed.

PACs ranging from the Air Conditioning Contractors of America to Potomac Electric and Power Co. gave to Parris as well, with particularly large infusions coming from the oil and banking industries.

Harris said he considered Parris' money advantage "between important and controlling . . . . I guess we've all learned that this kind of money buys a computer operation that's somewhere between impressive and frightening," said Harris, who had hoped to prove by his campaign that a strong volunteer effort by retirees, environmentalists and others can still prevail in an era of technologically sophisticated campaigning.

Parris aide Dick Leggitt said more than 7,000 individuals gave to the Republican's campaign, with PACs providing between a third and half of his funds. Harris received about half of his money from PACs. "I do not think money was the difference in the race," Leggitt said.