NOVELTY - Preparation of graphene loaded nano alloy catalyst comprises oxidizing and peeling graphite to obtain graphene oxide (GO) solution; using cation polyelectrolyte for surface-functionalizing GO; adding metal precursor, absorbing the metal ion with negative charge to the GO surface under static action; and in-situ reducing constraint metal ion, reducing the GO to be graphene to obtain high-dispersion graphene loaded nano alloy particle.    USE - Preparation method for graphene loaded nano alloy catalyst used as electrical catalyst for methanol fuel cell.    ADVANTAGE - The method solves the problems such as low particle dispersion, inconsistent reducing speed for two metal ions and non-uniform alloy component when the graphene is gathered and difficult to be dispersed, and the metal atom is grown on the surface defect part of the graphene.    DETAILED DESCRIPTION - Preparation of graphene loaded nano alloy catalyst comprises:    (A) oxidizing and peeling graphite to obtain GO solution;    (B) slowing adding cation polyelectrolyte aqueous solution to the GO solution, absorbing polymer molecule to the GO surface under the static cation of the polymer molecule with positive charge and the negative charge on the GO surface after agitating and mixing the mixed solution for certain time for realizing functionalizing for the GO; removing the remaining polymer to obtain the GO-polyelectrolyte composite solution, where the cation polyelectrolyte aqueous solution is poly(diallyldimethylammonium chloride) (PDDA), polydiallyl dimethyl ammonium chloride (PDADMAC), poly(dimethacrylate) (PDM), and polyacrylamide (PAM);    (C) adding metal precursor to the solution, absorbing the metal ion with negative charge to the GO surface under static action, where the metal ion is two of platinum hexachloride ((PtCl6)2-), palladium chloride ((PdCl4)2-), and gold tetrachloride ((AuCl4)-);and    (D) in-situ reducing constraint metal ion, reducing the GO to be graphene to obtain high-dispersion graphene loaded nano alloy particle.