The invention discloses a polyarylenesulfidesulfone hollow fiber and flat plate separating membrane and a preparation method thereof. The polyarylenesulfidesulfone hollow fiber and flat plate separating membrane is characterized in that 12-28 parts of polyarylenesulfidesulfone, 1-10 parts of polyvinylidene fluoride, 2-8 parts of hydrophilic polymer, 2-10 parts of an additive and 2-10 parts of a solvent are added into a dissolution kettle, stirred and dissolved at the temperature of 120-160 DEG C, subjected to centrifugal filtration to remove solid impurities and subjected to standing and defoaming for 2-4 hours, and polymer dope is prepared; the polymer dope is uniformly scraped on a glass plate by a flat plate type membrane scraping machine, a solvent is pre-evaporated for 10-60 seconds, a primary membrane is immersed into a coagulating bath for curing to obtain a polyarylenesulfidesulfone separating membrane, the temperature of the glass plate is 20-60 DEG C, the humidity is 50%-90%, and the temperature of the coagulating bath is 20-60 DEG C; or the polymer dope is sprayed from an annular spinning nozzle through wet spinning, passes by a 0-10 cm spinning line, is immersed into the coagulating bath and is stretched, wound and formed, a spinning core liquid adopts an ethanol solution with concentration of 50%, the temperature of the coagulating bath is 20-60 DEG C, the spinning humidity is 50%-90%, and the polyarylenesulfidesulfone hollow fiber separating membrane is prepared.