Both understanding and simulation of the process of corrosion damage are crucial for the prediction of remaining service life of engineering structures, sound reliability analysis, and design for the purpose of enhancing the overall resistance of the material to corrosion damage. A coupled mechano-electrochemical peridynamic (PD) corrosion model was established by using the PD corrosion theory and the mechanochemical effect theory. The model is capable of simulating the occurrence of degradation caused by the conjoint and mutually interactive influences of mechano-electrochemical phenomena. Corrosion behavior of TC18 titanium alloy in EXCO solution under stress loads of 31% σ0.2, 47% σ0.2, and 62% σ0.2 was studied. The effect of tensile loads on the corrosion behavior of TC18 titanium alloy was examined by combining the micromorphology and electrochemical parameters to verify the dependence of reaction rate occurring at the anode on tensile stress. Results of this study shed light that as the stress level increases, the corrosion potential of TC18 titanium alloy shifts negatively, the corrosion current density increases and the corrosion intensifies. When the phase transition mechanism is satisfied, boundary movement occurs spontaneously. This model can safely be employed for complex geometric shapes and as a basis for studying crack propagation in environments that are favorable or conducive for inducing corrosion.