The invention provides a method for preparing a porous-structure VO2 film with a polystyrene bead as a soft template. The method comprises the following steps: dissolving vanadium pentoxide (V2O5) and analytically pure oxalic acid (C2H2O4) in absolute ethyl alcohol and carrying out stirring in a beaker until the raw materials are totally dissolved; adding a small amount of polyvinylpyrrolidone (PVP) and carrying out stirring for 20 to 40 min; then transferring the obtained solution into a four-mouth flask and carrying out heating and stirring in an oil-bath pot with a temperature of 120 to 150 DEG C for 12 to 16 h; adding absolute ethyl alcohol emulsion in which the polystyrene bead is dispersed, adding a certain amount of an absolute ethyl alcohol solution of a surfactant P123 drop by drop and continuing stirring at room temperature until a uniform emulsion sol is formed; and after preparation of a wet film, drying the wet film in a baking oven at 100 to 150 DEG C for 10 to 30 min and maintaining the film at a temperature of 450 to 650 DEG C for 20 to 30 min under the protection of an Ar or N2 atmosphere so as to obtain the porous-structure VO2 film; wherein a mol ratio of the raw material V2O5 to the raw material C2H2O4 is 1: 3 to 1: 6, and the emulsion in which the soft template polystyrene bead is added accounts for 6 to 18% of the total volume of the sol.