Abstract: The isothermal tensile tests of Al-Si coated 22MnB5 high strength steel were carried out on Gleeble-3800 thermal simulation machine under the conditions of deformation temperature 750-900 ℃ and strain rate 0.1-10 s^-1. Based on the true stress-true strain data obtained from the tests, the Johnson-Cook constitutive model of Al-Si coated 22MnB5 high strength steel was constructed. It is found that the model has good prediction accuracy at lower deformation temperatures when the temperature sensitivity coefficient of reference strain rate is used, but the prediction ability is poor at other deformation temperatures. The influence of strain rate on the temperature sensitivity coefficient is characterized by second-order polynomial,and the modified Johnson-Cook constitutive model is obtained. The prediction accuracy is greatly improved and has good accuracy in the whole deformation condition. The ability of the Johnson-Cook and the Arrhenius constitutive models to describe the constitutive relationship of Al-Si coated 22MnB5 high strength steel was compared and analyzed.The results show that the ability of the Arrhenius model in predicting stress is slightly higher than that of the Johnson-Cook model. The Johnson-Cook model is better than the Arrhenius model in the tracking and description of the stress-strain curves.