The microstructural evolution of 617B Ni-base superalloy at different strain rates were studied by Gleeble3800 thermal simulation testing machine, optical microscope and electron backscatter diffraction. The results show that for the 617B alloy, when the strain rate≤1 s-1, the deformation temperature rise is negligible. When the strain rate≥10 s-1, the temperature rise is significant. As the strain rate increases, the peak strain of dynamic recrystallization tends to increase when in the same deformation temperature condition. In the range of strain rate of 0.1~20 s-1, the dynamic recrystallized grain size trend at first decreases and then increases as the strain rate increases.