The invention relates to a graphene oxide (GO)-coated PGMA (poly-glycidyl mathacrylate) microsphere composite anti-corrosive coating additive and a preparation method thereof. The GO-coated PGMA microsphere composite anti-corrosive coating additive is characterized in that PGMA microspheres with uniform particle size distribution and micrometer size are prepared by a single dispersing method; a surfactant CTAB (cetyltrimethyl ammonium bromide) is adsorbed to the surface of each microsphere, the ammonia ions in the CTAB are positively charged, and the long alkyl chain has lipophilicity, so thatthe surface of each microsphere is positively charged after the CTAB is adsorbed to the surface of each PGMA microsphere; the GO has huge specific surface area, and contains a large amount of electronegative oxygen-containing function groups, such as epoxy groups, hydroxyl groups and carboxyl groups, the positive ions can be effectively adsorbed by electrostatic adsorption, and the GO irregularlycoats the surface of the polymer microsphere, so as to obtain the GO-coated PGMA microsphere composite anti-corrosive coating additive.