Based on segment joint full-scale loading test of line 13 in Shanghai, the parameters of CDP model were calibrated and a 3-D damage-plastic FEM model for segment joint of shield tunneling was established combining the damage-plastic model for concrete in ABAQUS and the code for design of concrete structures. Under the interaction of moment and axial force, the whole damage and fracture process of concrete was studied. What's more, the relationship among moment, splaying amount, deflection and damage during four stages of the whole damage process was described in detail. The results show that the deflection-load curve is closely consistent with that of the test, and the segment joint of shield tunneling goes through four stages, which are global section compressed stage, small deformation stage, large deformation stage and joint contact-extrusion failure stage. Finally, based on the splaying amount, combining the deflection, moment, and the average value of tensile damage strip, the health evaluation index about the damage and failure of the segment joint was proposed.