NOVELTY - Reinforced double-component nanofiber porous film is obtained by spinning closed polyurethane prepolymer and polymer resin double-component through static spinning method, and treating the nonwoven fabric at high temperature such that end base of the polyurethane prepolymer is released to obtain isocyanate basic group.    USE - The reinforced double-component nanofiber porous film is useful as diaphragm for lithium ion battery.    ADVANTAGE - The reinforced double-component nanofiber porous film can be manufactured simply, has high porosity, thermal stability, and excellent ion permeability and wetness of electrolyte.    DETAILED DESCRIPTION - Reinforced double-component nanofiber porous film is obtained by spinning closed polyurethane prepolymer and polymer resin double-component through static spinning method, and treating the nonwoven fabric at high temperature such that end base of the polyurethane prepolymer is released to obtain isocyanate basic group, where -NCO bond of polyurethane prepolymer and -OH bond of water in air have crosslinked and self polymerized to obtain polyurethane. The film is a semi-penetration network structure with porosity of 60-80% and tensile strength of 2-3 times higher than that of the polymer resin single-component porous film. An INDEPENDENT CLAIM is included for method for preparing the double-component nanofiber porous film, which involves (a) dissolving polymer resin and polyurethane prepolymer double-component in a mass ratio of 8:92 in a solvent to obtain a uniform stable solution, where the concentration of the solution is 11-20 wt.%, (b) adding the solution into an injection pump of an electric spinning device, connecting a solution interface of the injection pump with an electrode of a high-voltage power source, and placing a grounded metal collecting device at the other side which is 10-25 cm away from the injection pump, (c) increasing the voltage of the power source and regulating the speed of the injected liquid flow of the injection pump, ejecting the solution from a flat-opening needle tip nozzle of the injection pump by effect of high-voltage electric field, collecting the solution in the metal collecting device, placing the obtained non-woven film in a vacuum drying box, decompressing the vacuum drying box for 10-16 hours, and obtaining the film after the film contains no solvent, (d) transferring the film into oven to treat it at 110-180 degrees C for 10-30 minutes, adding the film into a constant-temperature humidifying box at 90-110 degrees C and at a humidity of 50-75% to treat for 1-3 hour, and obtaining a composite film, (e) adding the composite film at air humidity of 50-70% and at 20-45 degrees C for 1-3 days, and obtaining the polymer resin and polyurethane double-component nanofiber porous film, where the polymer resin is poly(methyl methacrylate), polyvinylidene fluoride, polyvinylidene fluoride-hexachloroethane copolymer, polyethylene terephthalate or polyacrylonitrile resin.