NOVELTY - A polymer powder, monomer and solvent are added and irradiation grafting reaction is carried out, irradiated powder is mixed with monomer solution, and homopolymer and monomer are washed with methylbenzene. The polymer powder is converted, grafted polymer powder is stirred and dissolved in organic solvent, to obtain polymer casting film liquor. The membrane is washed with deionized water, to obtain polymeric membrane material. The membrane material is hydrolyzed, sulfoacid group and tert-amino are introduced by cation and anion exchange, to obtain amphoteric ion exchange membrane.    USE - Preparation of amphoteric ion exchange membrane.    ADVANTAGE - The method economically provides amphoteric ion exchange membrane with excellent chemical resistance and stability.    DETAILED DESCRIPTION - A polymer powder, reaction monomer and solvent are added into an irradiation tube, nitrogen is filled and sealed and mutual irradiation grafting reaction is carried out using 60Co ( gamma ) ray or electron beam. The polymer powder is located in the aerobic or oxygen free environment, and then irradiated powder is mixed with monomer solution, stirred and reacted for 1-6 hours, powder is removed out with irradiation grafting, and homopolymer and monomer are washed with methylbenzene. The polymer powder is converted with irradiation grafting into membrane material, grafted polymer powder is heated, stirred and dissolved in organic solvent, to obtain polymer casting film liquor. The obtained polymer casting film liquor is injected into plane and clean glass plate, thickness of liquor film is controlled at 20-100 microns with scraper and dried at 50-100 degrees C, to obtain film. The obtained film is washed with deionized water, grafted polymer powder is directly located in a hot-press and hot-pressing is carried out at 185-190 degrees C for 20-30 minutes under pressure of 8-10 MPa, to obtain polymeric membrane material. The membrane material is sulfonated and hydrolyzed, sulfoacid group is provided with cation exchange function, and membrane material is provided into hydrochloric acid aqueous solution for carrying out protonation reaction, and tert-amino is added with anion exchange function, to obtain amphoteric ion exchange membrane. The polymer powder is methylbenzene. The monomer (I) is styrene, alpha -vinyltoluene and trifluorobenzene ethylene. The monomer (II) is methacrylic acid dimethylamine butyl ester. The reaction solvent is acetone, isopropanol or dichloromethane.