The invention discloses a preparation method of a double-sided passivated crystalline silicon solar cell, belonging to the technical field of photovoltaic power generation. The preparation method comprises the following steps of: firstly, respectively carrying out surface precleaning and surface texturing on P-shaped single crystal silicon and a polycrystalline silicon wafer by adopting an alkaline solution and an acid solution; secondly, diffusing by using phosphorus oxychloride as a diffusion source to form a PN junction; thirdly, removing a phosphosilicate glass on the surface of the silicon wafer by adopting a chemical wet method, and etching the edge of the silicon wafer by adopting a plasma; fourthly, preparing a silicon nitride film on the surface of an emitting region of a P-type silicon wafer by adopting a plasma enhanced chemical vapor deposition method; fifthly, preparing a mixed phase film material of hydrogenated microcrystalline silicon and amorphous silicon by adopting a hot filament chemical vapor deposition method, depositing a film at one side of the P-type silicon wafer, and passivating the defects and a dangling bond on the surface of the P-type silicon wafer; and sixthly, sintering a screen printing back electrode and a screen printing positive electrode to form the solar cell. The invention lowers the probability of compounding photo-generated minority carriers on the back surface, enhances the long-wave light quantum efficiency and creates the conditions of transportation and collection of the photo-generated carriers.