Abstract: Enzymes for biodegrading PVA was obtained from the waste water and sludge through separating technology.Spectrophotometric analysis was employed to investigate the effect of modification of PVA by formaldehyde and glutaraldehyde on the biodegradability of PVA.The results revealed that the biodegradability of PVA acetals is inferior to that of the unmodified PVA,and declines as the acetalizing or cross-linking degree increases.FT-IR analysis of the samples before and after biodegradation indicated that fission occurs in the backbone of PVA acetals during the degrading process.