Abstract: The effect of process parameters of lipase on wettability of PET fabrics was studied in this paper. And the wettability of PET fabrics was characterized with capillary effect. SEM test indicated that the degradation of macromolecules in PET surface have occurred after lipase treatment, and the surface of PET fibers become rougher. Water contact angle from 121.5°of the control decreased to 59°of treated samples, which indicated the wettability of PET fabrics was significant improved. As increase of the concentration of lipase and treatment time, the capillary height of PET fabrics increased. And the capillary height increased first, then decreased with the increase of pH value and treatment temperature. The optimized pH value and treatment temperature were 7 and 40℃, respectively. The results showed that it was feasible for lipase to improve the wettability of PET fabrics.