For H156 hot work die steel, a single-pass thermal compression experiment was conducted by Gleeb-1500D thermal simulator under the deformation temperature of 850-1220 ℃, the strain rate of 0. 001-1 s-1 and the true strain of 0. 7, and the true stress-true strain curve was obtained by collected data. Then, the mathematical relationship between rheological stress and thermal deformation parameters was obtained, and a dynamic recrystallization model was established. Furthermore, the microstructure of experimental samples under different thermal deformation parameters was observed and analyzed by optical microscope, and the grain size model was established.Finally, the dynamic recrystallization behavior of H156 hot work die steel was simulated by finite element software DEFORM-3D, and the influences of thermal deformation parameters on the dynamic recrystallization behavior of experimental materials were explored. The results show that with the increasing of deformation temperature, and the DRX volume fraction increases, the distribution of DRX grains becomes more uniform. A large strain rate shortens the deformation time, reduces the DRX area, and the fine grains lack sufficient time for nucleation and growth. Therefore, increasing the deformation temperature and decreasing the strain rate are conducive to the completion of dynamic recrystallization, and the numerical simulation results are consistent with the experimental results, which verifies the accuracy of the model.