Former Republican congressman Stanford E. Parris announced yesterday he will run again for Congress, hoping to win back the seat he lost to Rep. Herbert E. Harris II (D-Va.) in 1974.

Parris, 50, disclosed his plans in a letter to Virginia Gov. John N. Dalton. Parris has been serving as Dalton's representative in Washington for the past year.

To get another shot at Harris, Parris first will have to capture the Republican nomination in a June primary. Former State Del. Robert Thoburn has already announced he will seek the Republican nomination.

Parris's decision means that Harris, a liberal Democrat in a swing district, is likely to face another major challenge. Two years ago, Harris defeated Fairfax County Supervisor Jack Herrity in a hotly contested campaign.

Harris has an opponent for the Democratic nomination in Lester Fettig, a former White House budget employee who ran unsuccessfully for the Virginia legislature last year.

Parris, who has been helping direct the presidential campaign of Ronald Reagan in Virginia, has long talked about a rematch with Harris, who defeated him 58 percent to 42 percent in an election that Parris contends reflected sentiment against Richard Nixon and the Watergate scandal.

Before taking the job as Dalton's liaison representative in Washington last year, Parris practiced law in Northern Virginia. A decorated Korean war pilot, Parris lives in Woodbridge with his wife and three children.