The invention discloses a phosphated polyphenyl ether proton exchange membrane and a preparation method thereof. The preparation method comprises the following steps of using gibbsite as the raw material, using a silane coupling agent to treat the surface, using fatty acid polyethylene glycol ester as a dispersant, and dispersing into an ethyl acetate solution, so as to obtain an activated solution; using 4,4'-diphenylmethane diisocyanate as a crosslinking agent, and performing crosslinking and modifying on polyphenyl ether in an alcohol solution, so as to improve the membrane forming speed ofthe polyphenyl ether; after crosslinking, blending with hydroxyethylidene-1,1-diphosphonate; using p-toluene sulfonate as a catalyst, so as to realize the esterification of alcohol and phosphonic acid. The preparation method has the advantage that by adding the gibbsite, the surface hardness and mechanical strength of the finished proton exchange membrane are effectively improved, so that the comprehensive property of the finished proton exchange membrane is improved.