Abstract: The compression deformation experiments with the deformation amount of 60% were conducted on 35CrMo steel ingot blank at deformation temperatures of 850-1 150℃ and strain rates of 0.01-50 s^-1 by using Gleeble-3810 thermal simulator. Combining with the characteristics of true stress-true strain curves, the influence of strain rate and deformation temperature on the microstructure of the steel was investigated. The results show that the microstructures of the tested steel all had dynamic recrystallization characteristics after compression deformation under different conditions. At the same strain rate, the dynamic recrystallization grains after compression became larger in size with the deformation temperature increasing; at the same deformation temperature, the dynamic recrystallization grains became smaller in size with the increase of the strain rate. After hot compression deformation, the grain size at different spots of the tested steel was different. The grains in the large deformation zone at the central area is the smallest in size, and with the increase of the vertical distance and the horizontal distance from the central area, the grain size gradually increased.