Abstract: Poly(vinylidene fluoride) (PVDF) membranes with molecular structure containing carbon-carbon double bonds were prepared by adding ethylamine into casting solution. Antibacterial monomer dimethylamino ethyl methacrylate (DMAEMA) was grafted onto the surface of PVDF membranes via ultraviolet without initiator and deoxygenation, which were then modified by benzyl chloride. The antibacterial properties of the membranes were studied, and the results show that the membranes with higher graft density have better antibacterial performance, and the performance is enhanced with the increase of graft density and contact time of bacterium with grafted membranes. Meanwhile, there is no significant change after dilute hydrochloric acid washing, which indicates that acid has no effect on the antibacterial properties of the PVDF membrane.