The invention discloses a preparation method of a photo-crosslinked sulphonated polysulfone ion exchange membrane. The method comprises the following steps that 1, sulphonated polysulfone with a certain sulfonation degree is dissolved in a solution prepared from N,N-dimethylformamide (DMF), stirring is conducted, and standing and cooling are conducted at room temperature; 2, a photoinitiator and a cross-linking agent are added in the solution obtained in the first step, stirring is conducted, a uniform solution is obtained, standing is conducted, and a membrane casting solution is obtained; 3, the membrane casting solution obtained in the second step is poured on a glass plate, an automatic membrane scraper is used for rapid scraping in the mode of being perpendicular to the glass plate, and a membrane is formed; 4, the membrane obtained through scraping in the third step is rapidly subjected to ultraviolet irradiation, the membrane is rapidly put in vacuum of 50 DEG C to 80 DEG C to be dried, and the photo-crosslinked sulphonated polysulfone membrane is obtained. The exchange membrane obtained through the method is good in chemical stability, low in swelling degree and high in ion exchange capacity.