A Washington lawyer pleaded innocent yesterday in U.S. District Court to 32 counts of mail fraud stemming from his alleged participation in a scheme that used false medical claims to bilk about $26,800 from insurance companies.

Floyd W. Anderson, 42, of 2710 Daniel Rd., Chevy Chase, was ordered to stand trial on the charges Dec. 16 by Judge Charles R. Richey.

A federal grand jury has accused Anderson of referring clients to doctors who knowingly prepared fraudulent medical reports and doctor bills which Anderson then mailed to 10 automobile insurance companies.

According to the indictment, the doctors charged for office visits that were never made, made false claims for medical services and exaggerated injuries. After the insurance companies settled the claim, a payment was made to the client with the remaining money being split between Anderson and the cooperating doctor, investigators said. The indictment said the claims were filed from October 1976 to July 1979.

Twelve of the 32 alledgedly false claims listed in the indictment were based on medical reports and bills supplied by Dr. Marshall D. Nickerson who earlier had been convicted for participating in a similar scheme along with former Washington attorney Harry L. Barnett.

Barnett, who was also convicted for his part in the scheme, had allegedly filed 200 false auto accident claims. Nickerson was listed as the treating physician in 23 of them.

Anderson is also under indictment in Atlanta, where a grand jury charged last July that he conspired to sell cheap gems for 30 to 40 times their value to customers in Washington and Atlanta. Bethesda gem dealer Lawrence Andrew Funt, 29, and an Atlanta man were also charged in connection with that case. Attorney John A. Shorter Jr., who represented Anderson yesterday, said that trial in the Atlanta case is scheduled for January.