The invention relates to the technical field of thin film materials, in particular to a nylon porous fiber film, a preparation method thereof, a two-way stretching nylon porous fiber film and a preparation method of the two-way stretching nylon porous fiber film. The nylon porous fiber film is of a core-shell structure, a shell layer is prepared from nylon, a core layer is prepared from carbon fibers, a micro-nano-nylon porous fiber film is prepared by a static electricity mode, and repeated hot rolling and two-way stretching and setting are implemented to prepare the nylon porous fiber film.The prepared two-way stretching nylon porous fiber film has excellent temperature resistance, high specific surface area and porosity and good mechanical property and is widely applied to the fields of packaging materials, filtering films, diaphragms and the like.