The invention relates to a carbon fiber surface electropolymerization treatment method. The method comprises the following steps: impregnating carbon fibers into electrolyte solution containing vinyl monomers and oxidative substances; electrifying the carbon fibers serving as a cathode to perform an electrolytic reaction; and forming a polymer film layer on the surfaces of the carbon fibers, wherein the reaction time is between 10 and 150 seconds; and the current intensity is between 1.5 and 35A/m<2>. The carbon fiber surface electropolymerization treatment method has the characteristics of improving clustering property of treated carbon fiber bundles, saving starching step, enhancing adhesive force between the carbon fiber and resin, improving mechanical properties of carbon fiber reinforced composite materials, along with simple method and low cost.