▎ 摘　　要

NOVELTY - A composite diaphragm preparing method involves reducing the graphene oxide film by cyclic voltammetry to obtain a first film layer, mixing the vinyl guanamine, adamantane, bromosulfonic acid and formamide uniformly, adding sodium hydroxide, stirring and rotary evaporating to obtain polymer ion solution. The vinyl trimethoxysilane, nano titanium dioxide and formamide are mixed uniformly, added ammonia water, placing in water bath and performed drying treatment to obtain modified powder. The polymer ion solution, the modified powder, the polymerization monomer and the surfactant are mixed uniformly at mass ratio of 7.8-8.2:0.3:2.6-3.0:0.2, and performed ultrasonic polymerization, after hot dipping with sodium hydroxide and washed with water to neutrality and dried to obtain a second film layer, and bonded the both sides of the second film layer to the first film layer to obtain the finished product. USE - Method for preparing composite diaphragm for fuel battery. ADVANTAGE - The method enables preparing the composite diaphragm with improved ion conductivity, and chemical stability. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a composite diaphragm prepared by the method.