Abstract: The poly(glycidyl methacrylate) grafted membrane(PP-g-GMA) were prepared by UV-photo-irradiation.Then,the active epoxy group of PP-g-GMA reacted with cysteine in alkaline solution to prepare the amphoteric membrane(PP-g-Cys).The grafted chains on membranes improved the hydrophilicity of membrane surface but blocked the membrane pores as shown by SEM photos.The improved hydrophilicity and the blocked of membrane pores cause the trend that the pure water flux increases with the rise of grafting degree and then decreases at high grafting degree.The isoelectric point(IEP) of 7.6% and 16.1% PP-g-Cys are at pH 7.2 and 6.5 respectively.