The present invention provides an electromagnetic shielding film preparation method. The method comprises the following steps: providing a carrier film layer, and preparing an insulating layer on the carrier film layer; performing conductive treatment on the insulating layer by means of vacuum plating; placing an insulating layer matrix having undergone conductive treatment in an alkaline electrolyte, and using an alkaline solution precipitation method to perform electroplating sedimentation on the surface of said matrix at least three times so as to prepare a metal shielding layer; placing the metal shielding layer in a micro-etching solution, and performing surface micro-etching to obtain a micro-etched layer; placing the micro-etched metal shielding layer in an acidic electrolyte, and performing acid solution sedimentation treatment at least once to prepare a foamed metal layer; and sequentially preparing a conductive adhesive layer and a protective film layer on a surface of the foamed metal layer, thereby obtaining an electromagnetic shielding film.