A preparation method of a Pt/graphene catalyst, comprising the steps of: performing an oxidation reaction with graphite powder according to a Hummers method to obtain graphite oxide by adding graphite powder, potassium persulfate and phosphorus pentoxide into a concentrated sulfuric acid at a temperature of 80°C, stirring uniformly and cooling for more than six hours, washing to neutral, drying to obtain a sample; adding the dried sample into 200 to 250mL of concentrated sulfuric acid, then adding potassium permanganate, heat preserving at a temperature of 0 to 20°C for 5 to 60 minutes, maintaining at a temperature of 35°C in an oil bath for 1 to 2 hours, slowly adding deionized water containing hydrogen peroxide to obtain a mixture; and hot filtrating the mixture when the color of the mixture becomes bright yellow, washing with hydrochloric acid and then filtering, drying under vacuum condition at a temperature of 60°C for 48 hours to obtain the graphite oxide; adding the graphite oxide into water and then ultrasonically dispersing to form a graphene oxide solution with uniformly dispersed monolithic layer; preparing a reverse micellar system containing surfactant, co-surfactant, oil phase, and chloroplatinic acid aqueous solution at room temperature; adding the graphite oxide solution into the reverse micellar system dropwise, and adding catalyst dropwise to perform a reduction reaction under a water bath heating condition to obtain an emulsion containing Pt and graphene; adding demulsifier into the emulsion dropwise to load Pt on the graphene carrier; and filtering, washing, and drying the graphene loaded with the Pt to obtain the Pt/graphene catalyst. performing an oxidation reaction with graphite powder according to a Hummers method to obtain graphite oxide by adding graphite powder, potassium persulfate and phosphorus pentoxide into a concentrated sulfuric acid at a temperature of 80°C, stirring uniformly and cooling for more than six hours, washing to neutral, drying to obtain a sample; adding the dried sample into 200 to 250mL of concentrated sulfuric acid, then adding potassium permanganate, heat preserving at a temperature of 0 to 20°C for 5 to 60 minutes, maintaining at a temperature of 35°C in an oil bath for 1 to 2 hours, slowly adding deionized water containing hydrogen peroxide to obtain a mixture; and hot filtrating the mixture when the color of the mixture becomes bright yellow, washing with hydrochloric acid and then filtering, drying under vacuum condition at a temperature of 60°C for 48 hours to obtain the graphite oxide; adding the graphite oxide into water and then ultrasonically dispersing to form a graphene oxide solution with uniformly dispersed monolithic layer; preparing a reverse micellar system containing surfactant, co-surfactant, oil phase, and chloroplatinic acid aqueous solution at room temperature; adding the graphite oxide solution into the reverse micellar system dropwise, and adding catalyst dropwise to perform a reduction reaction under a water bath heating condition to obtain an emulsion containing Pt and graphene; adding demulsifier into the emulsion dropwise to load Pt on the graphene carrier; and filtering, washing, and drying the graphene loaded with the Pt to obtain the Pt/graphene catalyst.