Abstract: Having discussed biodegradability of PVA,polyacrylic acids size,and sizing agents,the paper summarizes: raw starch and polyacrylamide size exhibit better biodegradability,and PVA is most difficult for biodegradation.Other sizes will cause contamination to some extent to the ecology.Most of the sizing agents are surfactants,among them,in the case of the hydrophobic ones,longer the carbon chain,more difficult to biodegrade,and the straight chain structure has better biodegradability than the branch one.For solving the problem of hard degradation of PVA,a new generation of biodegradation enzymes has been developed,which can fast biodegrade PVA waste liquor.