Abstract: The hot deformation behavior of 3Cr2MnNiMoBi steel at deformation temperature of 800-1150 ℃ and strain rate of 0.01-10 s^-1was studied by using the thermal simulation testing machine. According to the peak stress under different deformation conditions, the constitutive equation of the experimental steel was constructed, the hot deformation activation energy was calculated, and the hot processing map under different strain conditions was established based on the dynamic material model. The results show that during the hot deformation process, the increase of deformation temperature or the decrease of strain rate are conducive to the occurrence of dynamic recrystallization. At the same time, with the increase of strain, the processing instability zone of the experimental steel moves towards the high temperature and high strain rate zone,and the area of the instability zone gradually increases. The optimal hot working window of 3Cr2MnNiMoBi steel is（1060-1150）℃ ×（0.01-1）s^-1.