Abstract: The alkaline phosphatase from Anodonta woodiana Heude was selectively modified by PMSF DTT, PCMB, NBS, TNBS, SUAN BrAc and IAc, and changes in the activities of the enzyne have been detected. The reachon of AKP with PMSF NBS,TNBS, SUAN and DTT resulted in a strong inhibition of the enzyme activities which decreased with the increase of modifier concentration. The bromoacetic acid, iodoacetic acid and p-chloromercuri-benzoic acid were found without any inhibition effect Studies of inactivation of AKP by chemical modification demostrated that Ser, Lys and Trp residues are indirpensble functional groups of the AKP. Partial disulfide bond are also for the function of this enzyme.