Hot compression tests of a new type of AM80-0.2Sr-1.5Ca magnesium alloy were performed on Gleeble-1 500 at a strain rate of 0.01~1 s-1 and a deformation temperature of 300~450 ℃. The true stress-true strain curves and the strain hardening rate were obtained. The parameters of the modified L-J microstructure model, including the hardening parameter and recovery parameter, were calculated by combining the L-J model with K-M model. The evolution of the microstructure and dislocation density of the AM80-0.2Sr-1.5Ca magnesium alloy during the hot compression at 450 ℃ were simulated by using DEFORM-3D software. The results have shown that the recrystallized grains are larger and distribute non-uniformly when the strain rates are low, and the recrystallized grain size decreases with the increase of strain rate. The simulation results agree well with the experiments, which prove the accuracy of the L-J modeling for predicting the DRX process during hot compression.