The fracture failure performance and characterization model of high strength dual-phase steel DP780D+Z were studied. Based on fitting results of different hardening models, the combined hardening model was built by introducing the adjustment coefficient, and based on GISSMO and DIEM fracture failure models, the stress triaxiality and ultimate plastic strain under different failure modes were obtained by the combination of test and simulation methods. The optimal combined hardening model was obtained by taking the minimum error between the force-displacement curve output by the simulation model and the experimental test curve as the goal. According to different failure sample parameters, two fracture failure model curves were obtained by fitting, and through the error analysis between simulation and test of five different samples, a fracture failure characterization model with high comprehensive accuracy was obtained. The results show that when the adjustment coefficient is 0.527, the combined hardening model composed of Voce++ and Hockett-Sherby has the highest accuracy. The stress triaxiality in the fracture failure zone changes with the deformation of the sample, but the magnitude of the change is small. The comprehensive accuracy of both DIEM and GISSMO models is relatively high, but the accuracy of DIEM model reaches 97%, while that of GISSMO is 94%. Thus, based on comprehensive analysis, the DIEM fracture failure model has higher accuracy in characterization and can be used as a material fracture failure characterization model for vehicle simulation analysis.