Abstract: The hot compression tests of 20 CrMnTi steel were performed? using Gleeble-1500 D machine.The strain rates were0.01,0.1,1 and 5 s^-1 and the temperatures were 900,950,1 000,1 050 and 1 100℃.The effects of parameters on flow stress were analyzed via microscopic examination.The results show that the deformation conditions have significant effects on the microstructure of 20 CrMnTi steel after dynamic recrystallization.The flow stress decreases as deformation temperature increases and increases with the increase of strain rate.The deformation activation energy of 20 CrMnTi steel during hot deformation is327.8749 k J/mol by Arrhenius equation.