The building was turned over to her by the Klan as part of the judgment in a $7 million civil lawsuit brought against the Klan by Mrs. Donald for her son's death. In ruling in her favor, the jury concluded that a Klan organization was financially liable for the criminal acts of its members.

Two Klansmen have already been convicted in separate criminal proceedings for the slaying of Michael Donald, Mrs. Donald's 19-year-old son, who was beaten to death and his body left hanging from a tree on a street in Mobile. One of the men is awaiting execution and another is serving a sentence of life imprisonment.

By turning over to Mrs. Donald the building and property, the legal title to which was held by an organization called the Anglo-Saxon Club Inc. of Tuscaloosa, Ala., the Klan has decided not to appeal the judgment.

Although an all-white jury awarded Mrs. Donald a settlement of $7 million, Bill Stanton, an official of the Southern Poverty Law Center in Montgomery, Ala., said investigators searching since March had not been able to identify any substantial assets belonging to the Klan organization except the building. 'This Makes the Point'

''As far as we're concerned, this settles the thing,'' said Mr. Stanton, an investigator for the lawyers who represented Mrs. Donald in her lawsuit. ''We don't intend to pursue any further assets. This makes the point.''