Poly (lactic acid) (PLA) fiber has a tendency to undergo hydrolysis under wet conditions, which has restricted the application of PLA fiber. In this research, we report a new idea for improving the resistance of PLA fiber to hydrolytic degradation With controlled impairment of the fiber properties. The conventional pad-dry-cure method was used for hydrophobic finishing on PLA fiber inhibiting hydrolytic degradation to a great extent under the wet conditions studied. The evaluation Of the stability of finished and nonfinished PLA fibers was performed by examining the weight loss, surface morphology, molecular weight, tensile properties, and thermal properties of the samples after being treated with pH 7.4 buffers at 50 degrees C. Hydrophobic finishing of PIA fiber could be a simple and effective method to endow PIA fiber with good resistance toward hydrolysis, although the elevated curing temperature would cause slight damage to the fiber.