NOVELTY - An asymmetric perfluorosulfonic acid/polypropylene/sulfonated poly(ether ether ketone) composite membrane preparation method involves putting (in mass %) dried perfluorinated sulfonic acid resin (2-40) in high boiling point organic solvent and heating, followed by dissolving in a reaction kettle. The obtained solution is subjected to perform ultrasonic process to remove bubble and impurities. The obtained solution is added with a glass plate and soaking a polypropylene diaphragm in the resultant solution at 30-160 degrees C for 1-18 hours, followed by drying to get composite perfluorinated membrane.    USE - Method for preparing an asymmetric perfluorosulfonic acid/polypropylene/sulfonated poly(ether ether ketone) composite membrane.    ADVANTAGE - The method enables preparing composite membrane with better vanadium resistance performance, mechanical property, chemical stability and better single vanadium redox flow battery performance in a simple, cost-effective and eco-friendly manner.    DETAILED DESCRIPTION - An asymmetric perfluorosulfonic acid/polypropylene/sulfonated poly(ether ether ketone) composite membrane preparation method involves putting (in mass %) dried perfluorinated sulfonic acid resin (2-40) in high boiling point organic solvent and heating, followed by dissolving in a reaction kettle. The obtained solution is subjected to perform ultrasonic process to remove bubble and impurities. The obtained solution is added with a glass plate and soaking a polypropylene diaphragm in the resultant solution at 30-160 degrees C for 1-18 hours, followed by drying to get composite perfluorinated membrane and preparing a sulfonation product by adding (in weight parts) polyether-ether-ketone 1 with sulfuric acid (10-70). The obtained acid mixture is subjected to perform sulfonation reaction in an ice water bath and stirred, followed by decompressing, filtering and washing the sulfonation product repeatedly until it reaches neutral. The washed product is dried to get sulfonated poly(ether ether ketone) solution, which is dissolved in high boiling point organic solvent with a mass volume ratio of 1/5-1/100 g/ml to the sulfonated poly(ether ether ketone) solution. The obtained solution is coated on composite perfluorinated membrane and dried, followed by demolding to get asymmetric perfluorosulfonic acid/ polypropylene/sulfonated poly(ether ether ketone) composite membrane.