In order to improve the fracture toughness of DP980 steel, niobium microalloying was conducted and its mechanical properties were evaluated by CAE simulation technology. For DP980 steel with and without niobium, the quasi-static and high-speed tensile tests of DP980 steel were conducted. The experimental results show that niobium can effectively improve the fracture toughness of the material which is not sensitive to strain rate, and Swift+Hockett-Sherby constitutive model can be well used to describe its strain-hardening properties. Combined with DIC technology, the tensile tests of R5 notch, R10 notch, pure shear, tensile shear and center-hole and the cupping test of DP980 steel were conducted. It is found that the fracture performance of the material is sensitive to the stress state. The MMC fracture failure model was used for simulation, and the result shows the simulation accuracy is high，which proves that the failure model can accurately characterize the fracture failure behavior of the material. The three-point bending test simulation of DP980 steel with and without niobium anti-collision beams was conducted respectively, and the simulation results show that DP980 steel with niobium has better collision performance. The research result provides a reference for the simulation analysis on the fracture failure of materials and parts and the vehicle collision for high strength steel with niobium.