Prince William County is revising its affirmative action policy to bring it in line with 1980 Census figures showing an increase in the number of blacks in the county.

Last month, two black citizens threatened to sue the county because they said qualified blacks were being turned down for county jobs. "It seems this can be resolved without litigation," said Vic Glasburg, attorney for Lorene Jackson, one of the residents who had threatened to sue. "I have talked with the county attorney and they seem aware of the problem. They plan aggressive affirmative action."

Prince William County Executive Robert Noe would not say, however, if the decision to revise the policy is in response to the threatened lawsuit. He said, through county spokesman Michael Gleason this week, that the affirmative action plan is being updated because the county recently received 1980 Census figures that show the black population in the county has increased. The current plan, adopted in May 1980, is based on the 1970 Census.

The two black residents threatened to sue last month after they and three other blacks had what they said was an unsatisfactory meeting with county Personnel Director Cleil W. Fitzwater. The residents also complained to the Board of Supervisors at a board meeting the following week about the policy, which they said was outdated. Board members made no comment in response to their presentation.

The 1970 Census showed a 5.3 percent black population in the county, and the current affirmative action plan calls for a minimum of 5.3 percent black county workers by June 1982.

Gleason said the county actually had 5.7 percent black county workers by June 1982, four-tenths of a percent above the target goal. But he said the 1980 Census showed that now 7.7 percent of the available work force in the county is black.

He said the new affirmative action policy would shoot for a 7.7 percent black employment rate in the county work force. He said the updated policy is expected to be presented to the board in mid-October.

Duane M. Turner of the county personnel department said local officials from the NAACP have been consulted on the new affirmative action policy. The NAACP was not involved in the original complaint against the county.

Turner said the new policy does not as yet, specifically call for the appointment of an affirmative action officer, a demand made by the residents who threatened the suit. He said Fitzwater, who could not be reached for comment, acts as the officer along with his other duties.