Washington has scored high marks in the technical tests--financing, security and congeniality--for cities seeking the party's 1984 national convention, Democratic Party officials touring the city said yesterday.

But in the five-city battle for the convention, the winner is likely to be the city that provides what party leaders believe would be the best vehicle for Democrats to launch their assault on the Reagan White House, officials said.

San Francisco, the early frontrunner, still is seen as having the advantages of being in the West, a region that the party desperately wants to return to the Democratic column, and of being a potentially large source of vital campaign funds, according to sources close to the site selection committee.

Washington suffers from being the nation's capital, with only three electoral votes, and from an image of being synonymous with big government.

Nevertheless, party officials said that they were impressed by the city's presentation.

"There was some feeling that Washington was not serious, but all of that has since disappeared," Ray Majerus, the site selection committee's chairman, said yesterday as the panel finished the second day of its three-day visit here.

The panel already has visited New York and Detroit, as well as San Francisco, and will go to Chicago later this month before making a final decision on April 21.

Throughout yesterday's presentation, which began with a labor breakfast that appeared to favorably impress union-conscious party officials, Democratic bigwigs continued to praise the city, particularly what they felt was a well-orchestrated, smooth promotional campaign put on by Mayor Marion Barry and his aides.

Noting that political stability is crucial to the site selection, Peter Kelly, national party finance chairman and vice chairman of the site selection committee, said that Barry was "just about as tough, stable and competent as anyone would want to be."

Kelly called "ingenious" Barry's decision to make Maryland and Virginia part of the city's pitch. Gov. Charles S. Robb hosted a dinner for the site committee at the Madison Hotel in Washington last night, and panelists will conclude their visit today at a luncheon with Gov. Harry Hughes in Annapolis.

Richard Murphy, chairman of the party's Technical Advisory Committee, praised Police Chief Maurice Turner and his staff, who briefed committee members yesterday, and said that it was the best security presentation the committee has received so far. Committee concern about the relatively small size of San Francisco's police force is a chief weakness in that city's bid.

At a news conference yesterday, Barry said that the entire effort is likely to cost nearly $300,000, a figure that an informed source said would rise to $500,000 if complimentary air fares and hotel rooms were included.

"I don't think you spend that kind of money if you're just fiddling around," Barry said.

Majerus, who is a union official from Wisconsin, said that he was "very much impressed" with the labor breafast, attended by about 150 persons and put on by the Metropolitan Washington Council, AFL-CIO and its president Joslyn N. Williams.

"You don't often think of Washington, D.C. as having that kind of viable, labor movement," Majerus said.