Abstract: The hot compression test of Inconel 617 alloy was carried out at 1000 ℃-1200 ℃and the strain rate of 0.001 s^-1-1 s ^-1 by the thermal simulation testing machine. Electron backscatter diffraction and transmission electron microscopy techniques were used to investigate the microstructure evolution and the characteristics of geometrically necessary dislocations(GND) during hot compression. The results show that with the increase of temperature and the decrease of strain rate, the degree of recrystallization increases, the density of GND decreases, and the obvious adiabatic heating effect accelerates the nucleation and growth of recrystallization.During the thermal deformation of Inconel 617 alloy, a large number of dislocation walls are entangled with each other.GND first accumulates at the large angle grain boundary, then forms sub-grain boundary, and finally evolves into recrystallized grain.