Acrylic acid modified epoxy resin containing terminal double bond with the partial retention of epoxide group was synthesized. A stable waterborne epoxy-acrylate composite emulsion containing modified epoxy resin acrylate polymer (core) –inert polyacrylate (intermediate layer) -carboxyl acrylate polymer (shell) was successfully prepared by emulsion copolymerization and characterized by structural design. And the corrosion resistance of the composite latex films was studied. The results show that there is a successful emulsion copolymerization between modified epoxy resin and acrylate monomer, and the obtained composite emulsion has the partial retention of epoxide group and the introduced carboxyl group; the stability and corrosion resistance of the three-layer composite emulsion with intermediate layer are better than those of the conventional core-shell emulsion, and the set intermediate layer can indeed play an expected role; the mass fraction of intermediate layer has great influence on the corrosion resistance of coatings. When the mass fraction of intermediate layer is 26%, the thickness of the middle layer calculated by temperature random multi-frequency modulation DSC is 14.51 nm, |Z|0.01Hz is 1.66×104 Ω?cm2 for the three-layer core-shell coatings after the 7d immersion of 3.5% NaCl solution, and the content of iron on tinplate remains 95.29% after immersed in 3.5% NaCl solution for 3 d, the coatings are peeled off to expose the steel surface.