The invention belongs to the field of painting, and particularly relates to acrylic acid modified epoxy phosphate resin and an aqueous dispersion thereof. In the formula, the acrylic acid modified epoxy phosphate resin is prepared from 40-45 parts of epoxy resin, 20-30 parts of a solvent, 0.4-0.5 part of phosphoric acid, 8-12 parts of acrylic acid (ester) monomer of which acrylic acid accounts for 1.4-2 parts, 0.5-0.8 part of an initiator, 3.2-5.2 parts of neutralizer and 80-100 parts of water. The resin is prepared by the following steps: modifying epoxy resin with phosphoric acid, and reacting with acrylic acid and ester monomers thereof; adding the neutralizer and deionized water, stirring and emulsifying to obtain the acrylic acid modified epoxy phosphate aqueous dispersion, wherein the acid value of the emulsion is 10-12mgKOH/g, and the solid content is 28-38 percent. The prepared main resin dispersion body is epoxy resin, has a phosphate structure, and has a good adhesive force for metal base materials, thus having good corrosion resistance; acrylic resin is modified, introduced with carboxyl and neutralized by the neutralizer to give aqueous dispersion to resin, so that the resin can be produced into water-borne painting, and the content of VOC is greatly reduced; and multiple hydroxyl radicals are arranged on the main chain of the epoxy resin, and can be crosslinked with amino resin, urea resin and phenolic resin to produce stoving varnish.