Fairfax County police yesterday reported a 27 1/2 percent decrease in critizen complaints against officers during 1979.

There were 95 complaints, compared with 132 in 1978, in the summary issued by Police Chief Col. Richard A. King. There were 121 complaints in 1977.

Of the 95 complaints last year, 27 were upheld after departmental investigations.In those cases, one officer was suspended, one assessed a day off without pay, nine received letters of reprimand and 20 received oiral reprimands. No officer was dismissed from the force as a result of any complaint.

King said it was too early to say whether the new citizen advisory councils he established in May 1979 in each police district and countywide were a factor in the drop in complaints.

The councils are a sounding board of neighborhood views on police-community relations, but they are not empowered to review how the police department's internal affairs unit handles citizen complaints.

In early 1979, a group called Fairfax County Citizens for Improved Law Enforcement and Community Relations called for citizen councils that could review cases, but King rejected this proposal.

The Citizens for Improved Law Enforcement was formed early last year after the widely reported Donald Ferguson case in which a young black man died at Western State Hospital after his arrest in Fairfax and jailing there.

In his report yesterday, King said that as a result of complaints from within the department during 1979, one officer was dismissed and four officers resigned. King said none of the cases involved allegations of excessive force.