The gravitational thermal analysis,machine intensity analysis and contact angle determination were employed to characterize the performance of Polyvinylidene Fluoride membrane after hydrophilic modification.At 0.2MPa,the modified membrane was applied to separate the oily wastewater which oil concentration was lower than 200mg/L,and oil rejection effect of modified membrane was studied.The results show that the thermal stability and machine intensity were improved compared to Polyvinylidene Fluoride membrane.After modification,water contant angle was minished to 35°,pure water flux is over 115L/m2·h,and oil rejection ratio was higher than 85%.The performance of modified membrane is better than that of Polyvinylidene Fluoride membrane.