Abstract: Methyl methacrylate (MMA) was grafted to the surface of polyethylene (PE) separator using a bulk surface photografting process irradiated by ultraviolet (UV), to improve the wetting ability of separator to the electrolyte solution. Results show that MMA could be efficiently grafted by UV irradiation, and the grafting degree reached 49.15% with an initiator mass concentration of 0.10 g/mL and a reaction time of 150 s. The change of surface morphologies was observed by SEM and AFM. Static contact angle test show that the contact angle of separator to the electrolyte solution decreased from 47.8°—48.1° to 18.1°—20.4° after treating, means the improvement of wetting ability.