Abstract: Poly(methyl methacrylate)(PMMA) was grafted onto poly(vinylidine fluoride)(PVDF) films pre-irradiated electron beam(EB). The influence of the radiation dosage, monomer concentration, reaction temperature and time as well as solvent on the grafting reaction was studied. Results showed that grafting rate increased with the radiation doseage. With the increase of monomer concentration, the grafting rate increased quickly at the preliminary stage and increased slowly above 40% and then reached a maximum when the monomer concentration was 70%. Grafting rate increased slowly below 40℃, and increased fast at 60℃, and then remained unchanged. Alcohols were effective solvents for the graft polymerization. The composition of the grafted film was analyzed using FT-IR, and the thermal performance of the grafted film was characterized by DSC. The FT-IR showed that the grafted film was a PVDF-g-PMMA copolymer. A thermal transition appeared at 117℃ and became more marked with the grafting yield. The melting peak moved to the left and disappeared finally with the grafting rate, which proved the grafting of PMMA broke down the PVDF film's crystallinity. At the DOG of 50%, the liquid uptake volume was 290% and the conductivity was 6.0×10^-3 S/cm.