A 3-D finite element model of the glass fiber composite laminates is established using vacuum-assisted wet-layup stepped-repair, and the tensile failure process is simulated. The anisotropic continuum damage mechanics model of lamina is developed considering the shear nonlinearity, and it is used to simulate the material failure of the parent and the patch laminates. The contact analysis is defined for the secondary curing interface between the motherboard and patch, using the cohesive model to achieve the interface contact properties. The test results are in good agreement with the numerical simulation results, and the model can be used to predict the tensile properties of the entire repaired structure. Finally, the damage and failure process of the step-repaired structure is analyzed during stretching.