In order to study the effect of elastoplastic deformation on the corrosion electric field of ships, a mechanochemical coupling model of corrosion electric field was established by using the solid mechanics and the secondary current distribution modules in the COMSOL simulation software based on the corrosion defect of ship hull surface. Two physical fields were solved by using the sequential solver setup, and the structural stress-strain simulated by the solid mechanics module was coupled to the expressions of equilibrium potential and exchange current density of electrode reaction, which were taken as the boundary conditions of the secondary current distribution module. Results show that the deformation of the hull structure caused the stress concentration at the corrosion defect, and the metal corrosion potential shifted negatively due to the mechanochemical effect. The existence of potential gradient in solution provided driving force for the current flow, thus forming the stress corrosion couple. Moreover, the center of the defect was anode and both sides of the defect were cathodes. When the corrosion defect was elastically deformed, the modulus of corrosion electric field generated by stress corrosion couple was small, while the corrosion electric field increased significantly when the corrosion defect was plastically deformed.