A 33-year-old staff attorney for the U.S. Department of Education plunged seven stories to her death yesterday from the top of the Hubert H. Humphrey federal building at Second and C streets SW.

D.C. police said there was no evidence of foul play and tentatively ruled the death a suicide.

The victim was indentified as Susan C. Steward of the 1700 block of Corcoran Street NW. Steward's body was found on a sidewalk along the east end of the Humphrey building. An autopsy was incomplete yesterday, but police said she apparently died of multiple injuries from the fall.

Friends and associates described her as "energetic" and "committed," both in her work and during the past several years that she worked as a volunteer and board member of the local American Civil Liberties Union chapter.

She resigned from the ACLU board earlier this year during an internal dispute over the firing of another employe.

A 1965 graduate of Washington-Lee High School in Arlington and a graduate of the University of Washington. Steward served in the Peace Corps and the Department of Labor while earning a law degree at the Georgetown University Law Center.

She joined the chief counsel's office of the old U.S. Department of Health, Education and Welfare in 1974 and moved to the Education Department after it was formed.

Education Secretary Shirley M. 'ufstedler, in New York for the democratic National Convention, issued a statement praising Steward as an "outstanding employe and a dedicated worker. We deeply regret her loss."