Abstract: Quasi-static tensile test with strain rate of 0.000 5 s^-1 and dynamic tensile tests with strain rates of 0.1—500 s^-1 were carried out on SUS301L-MT stainless steel at room temperature. The stress-strain curves of the stainless steel were obtained based on the classical J-C model fitting. The strain rate sensitivity coefficient was determined by the maximum fitting goodness and matching goodness, and the simulation accuracy of the classical J-C constitutive model was analyzed. The J-C model was modified by introducing the dynamic amplification modulus to determine the critical strain of martensitic transformation strengthening and adiabatic temperature rise softening, and the fitting results of the modified model were verified. The results show that the classical J-C constitutive model could not accurately describe the martensitic transformation strengthening effect and adiabatic temperature rise softening effect of test steel under high strain rate plastic deformation. The modified J-C constitutive model could accurately describe the mechanical behavior of the test steel when the strain rate was 0.000 5—500 s^-1, and its matching goodness was as high as 0.985, indicating that the model was reasonable and effective.