The hot tensile deformation behaviors of rolled ME20M magnesium alloy at temperatures of 623-773K and strain rates of 0.001-0.1s_^-1 were studied by INSPEKT Table 100kN universal high temperature experimental machine. The effects of deformation temperature and strain rate on the flow stress of the material were analyzed, and the constitutive model and processing map under hot deformation conditions were established. The results show that the flow stress of the rolled ME20M magnesium alloy increases with the decrease of deformation temperature or the increase of strain rate. The predicted peak stress of the constitutive model is in good agreement with the experimental results, and the average relative error is 5.19%. After considering the influence of strain on the material constant in the constitutive model, the predicted stress value is highly correlated with the experimental value, and the average relative error is 6.00%. The best hot working range is 673-773K, the strain rate of 0.001-0.01 s_^-1.