Abstract: The compression deformation test of as-rolled TC21 alloy in α+β two-phase region was carried out by using Gleeble-3500 thermal simulation test machine. The microstructure and flow stress curves of the alloys at different hot deformation temperatures (870-960℃) and strain rates (0.001-1 s^-1) were studied. The flow stress constitutive equation and dynamic recrystallization dislocation density model were established, and the microstructure was simulated and verified. The results show that the softening mechanism of flow stress curve of the alloy was mainly dynamic recrystallization. When the strain rate was constant, the content of α phase in the deformed microstructure decreased continuously with increasing deformation temperature, and the size of α phase increased first and then decreased. When the deformation temperature was 870℃ and 900℃, the size of α phase decreased first and then increased with increasing strain rate. When the deformation temperature reached 930℃, which was close to the transformation point, the α phase content decreased sharply, and the β phase grain was dynamically recrystallized, and the grain size was refined. The established stress calculation model was used to predict the peak stress, and the results were relatively accurate with an average relative error of 6.274%. The simulation results of the dynamic recrystallization microstructure based on the flow stress constitutive equation and the dislocation density model were basically consistent with the microstructure obtained by the experiment, and the calculation model was relatively accurate.