LOS ANGELES (AP) _ The National Journal, an award-winning magazine covering national politics and government which charges $546 for an annual subscription, has been acquired by The Times Mirror Co.

To buy the magazine, Times Mirror purchased from National Journal founder Anthony Stout all the shares of the Government Publishing Corp. which held an 80 percent interest in The National Journal. Times Mirror also bought the remaining 20 percent of the stock of the magazine from the Washington Post Co.

''The National Journal is a highly respected source of information on the workings of our government,'' Robert F. Erburu, Times Mirror's chairman, president and chief executive, said Tuesday. ''This acquisition will add luster to the company's reputation as a leader in providing distinguished journalism.''

Terms of the agreement were not disclosed. The National Journal is a 17-year-old, weekly publication with a circulation of approximately 5,000.

A two-time National Magazine Award winner, the publication's emphasis is on national politics and government. It has a reputation for in-depth analysis of government activity.

Subscribers include members of Congress, White House staff members, federal agency leaders, journalists, lobbyists and senior corporate executives.

Stout, one of the founders of the National Journal and the magazine's owner since 1975, said, ''We are delighted to join Times Mirror, a company recognized for excellence in its field. This surely enhances the future of the National Journal.''