Mayor Walter E. Washington has expanded his publishing enterprises with a new slick-paper book detailing what his administration has done to improve the city in the 10 years since the 1968 riots.

At a taxpayer-financed cost of about $6,500, the mayor published 3,000 copies of "A Report to the People . . . A Decade of Progress for the District of Columbia."

Many copies already are on their way to city officials, libraries, community organizations and advisory neighborhood commissions, and some will be available to the public for the asking.

The book came off the press 10 years after Martin Luther King's assassination touched off three days of burning and looting. The timing also on precedes the mayor's expected announcement that, after 11 years in the city's top office, he will seek reelection.

The 10-year report is the mayor's second recent entry into the publishing field.

Last month, he converted the D.C. Pipeline, a newsletter for municipal employes, into City News, a more widely distributed tabloid containing laudatory reports on his administration's activities.

Except for the four presidents who have occupied teh White House during the past decade, the anniversary report mentions almost nobody by name except Walter Washington, who is mentioned frequently.

The D.C. City Council, the city's legislative body, is mentioned often in institutional terms, but there is no personal identification of any individual who sat on the council - including its four chairmen.

"It is a 10-year history of the executive branch of the District of Columbia government," said John H. Drof, a city employe, who said he produced the text of the 76-page document largely on his own time, at night and on weekends. "With the mayor being the mayor, I just mentioned his name when it was appropriate."

Drof is a special assistant to Ben W. Gillbert, director of the Municipal Planning Office, and a close personal friend and advisor to the mayor.

Sam Eastman, the mayor's press secretary, said hte mayor agreed to a suggestion by Gilbert that the anniversary book would be a good idea. In January, the mayor circulated a memorandum to all department heads directing them to catalogue the achievements of the past decade.

"I knew when I got that memo that the mayor was going to run for reelection," one middle-level city official remarked recently.

Eastman grimaced when a reporter suggested the report might become a useful campaign document."

Behind a front cover in brown ink that reproduced a child's drawings of a city in flames alongside a city restored, the book reviews what has happened to virtually every program under city control, and some that are not. Pictures of new buildings and other municipal improvements are plentiful.

For any who doubt that the city is doing its job well, the report pointed out that municipal agencies have been reorganized by the mayor along functional lines "to assure more efficient and effective operations."