NOVELTY - Raw materials are provided under protection of nitrogen, 2,2'-benzidinedisulfonic acid, m-cresol and triethylamine are provided in reactor and stirred. The reacted material is poured in precipitator acetone, filtered and dried, to obtain triethylamine salt-sulfonated polyimide. The obtained product is dissolved in organic solvent and soaked, and film is removed out and washed by using deionized water, to obtain sulfonated polyimide proton conductive film. The obtained film is soaked and dried, to obtain sulfonated polyimide/chitosan composite proton conductive film.    USE - Preparation of sulfonated polyimide/chitosan composite proton conductive film.    ADVANTAGE - The sulfonated polyimide/chitosan composite proton conductive film is efficiently prepared.    DETAILED DESCRIPTION - Raw materials containing (in mmol) 1,4,5,8-naphthalene dianhydride (2), 2,2'-benzidinedisulfonic acid (0.4-1.6), 4,4'-diamino diphenyl ether (0.4-0.6), catalyst (2.4-4), releasing agent triethylamine (0.8-6.4) and solvent m-cresol (90-185) are provided under protection of nitrogen. 2,2'-Benzidinedisulfonic acid, m-cresol and triethylamine are provided in a reactor, stirred at room temperature until the solid is dissolved, then 1,4,5,8-naphthalene dianhydride, benzoic acid and 4,4'-diamino diphenyl ether are added, stirred and heated at 70-100 degrees C, reacted for 2-4 hours, then warmed at 180-220 degrees C to react for 10-20 hours, and cooled at 80 degrees C. The reacted material is poured in a precipitator acetone, filtered, solid is washed by using acetone for 2-3 times, and then dried at 60-120 degrees C for 10-30 hours, to obtain triethylamine salt sulfonated polyimide. The obtained sulfonated polyimide is dissolved in the organic solvent to prepare the solution with concentration of 5-15 %mass, and solution is cast on a clean and smooth glass plate to form a film. The glass plate adhered is dried with film at 60-120 degrees C for 15-36 hours, film is peeled off from the glass plate, and soaked in the washing agent acetone for 10-24 hours and sulfuric acid water solution (1-2.5 mol/L) for 10-36 hours. The film is removed out, and washed by using deionized water for 2-4 times until the pH is 6-8, to obtain sulfonated polyimide proton conductive film. The obtained film is soaked in the deionized water, chitosan (in parts) (1), p-toluenesulfonic acid (1) and water (25-100) are added and mixed to prepare the p-toluenesulfonic acid solution of the chitosan. The sulfonated polyimide proton conductive film is soaked in the p-toluenesulfonic acid solution of the chitosan for 2-48 hours, removed and dried at 30-80 degrees C for 5-15 hours. The dried film is soaked in sulfuric acid solution (1-6 mol/L) for 2-20 hours and deionized water for 2-10 hours, and deionized water is changed for 2-3 time in the soaking process and removed out, to obtain sulfonated polyimide/chitosan composite proton conductive film. The volume ratio of precipitator acetone and reacted material is 5-20:1. The thickness of the film is 10-200 mu m. The organic solvent is m-cresol, N,N-dimethylformamide, N,N-dimethylacetylamide, dimethylsulfoxide and/or N-methyl-N-pyrrolidone.