Manufacturing method of porous polyimide film

The invention relates to a manufacturing method of a porous polyimide film, comprising the following steps of: synthesizing organic dianhydride, or organic diamine and a pore-forming material to obtain a polyamide acid copolymerized resin solution, followed by biaxial stretching and imidization after film forming, and pickling to remove the pore-forming material to obtain the porous polyimide film, wherein the mol ratio of organic dianhydride to organic diamine is 1:1; and the pore-forming material is any one or more components selected from calcium oxide, calcium carbonate, magnesium oxide and magnesium carbonate, the particle size is 0.01-5.0 micrometers, and the use amount is 0.25-2 times, preferably 0.43-1 time, the sum of the weight of organic dianhydride and the weight of organic diamine. The steps contain: preparing materials, pouring diamine into a solvent for one time, stirring and dissolving, pouring dianhydride for several times, pouring the pore-forming material into the residual solvent, uniformly stirring, and pouring into a reaction vessel. A polyamide acid resin solution is obtained after the resin viscosity reaches 40-70 thousand centipoises, and then subsequent steps are carried out. The particle size and amount of the pore-forming material determine the aperture of the film. The manufacturing method provided by the invention is easy to control.