NOVELTY - Preparing proton exchange membrane comprises (a) dispersing a perfluorinated sulfonic acid resin in a organic solvent for preparing perfluorinated sulfonic acid resin solution, (b) adding organic heat stabilizer and aromatic diamine in obtained solution and adding aromatic tetracid dihydride to obtain polyamide acid perfluorinated sulfonic acid resin solution, (c) coating polyamide acid solution on a glass plate and drying to obtain polyamide acid perfluorinated sulfonic acid resin proton composite membrane, and (d) soaking obtained composite membrane, dewatering and cyclizing mixed solvent.    USE - The method is useful for preparing proton exchange membrane.    ADVANTAGE - The method is capable of preparing proton exchange membrane with high conductivity and good high temperature resistance performance in a safe and an economical manner.    DETAILED DESCRIPTION - Preparing proton exchange membrane comprises (a) dispersing a perfluorinated sulfonic acid resin in a organic solvent with high boiling point for preparing the perfluorinated sulfonic acid resin solution, where the high boiling point of the organic solvent is 140-205 degrees C, (b) adding a organic heat stabilizer and aromatic diamine in the perfluorinated sulfonic acid resin solution and adding a aromatic tetracid dihydride to obtain a polyamide acid perfluorinated sulfonic acid resin solution, (c) coating the polyamide acid perfluorinated sulfonic acid resin solution on a glass plate and drying to obtain polyamide acid perfluorinated sulfonic acid resin composite membrane, and (d) soaking the polyamide acid perfluorinated sulfonic acid resin composite membrane in a mixed solvent, dewatering and cyclizing the mixed solvent at room temperature to obtain the polyimide perfluorinated sulfonic acid resin proton exchange membrane, where the mixed solvent includes a acetic anhydride and pyridine. An INDEPENDENT CLAIM is included for polyimide perfluorinated sulfonic acid resin proton exchange membrane, where the perfluorinated sulfonic acid resin is diffused in the polyimide porous membrane.