Abstract: Quasi-static compression at low strain rates (10^-4, 10^-3, 10^-2 s^-1) and dynamic compression at high strain rates (850-4 500 s^-1) were conducted on 38CrMoAl high strength steel with a hydraulic testing machine and a split Hopkinson pressure bar test device. The dynamic compressive mechanical properties of the steel and the microstructure after dynamic compression were studied. Considering the strain rate enhancement effect and adiabatic effect, the Johnson-Cook (J-C) constitutive model was modified, and was verified by experiments. The results show that the true yield strength of the test steel increased with the increase of the compressive strain rate, indicating an obvious strain rate enhancement effect. After compression at high strain rates, the strengthening zone with certain corrosion resistance appeared in the microstructure of the test steel. The average relative errors between the prediction by the modified J-C constitutive model and the experimental values of the true stresses were 1.76%-3.99%, indicating that the modified J-C constitutive model could describe the dynamic compressive mechanical properties of 38CrMoAl steel accurately.