Abstract: Aiming at the problems such as hot deformation hardening, cracking and coarse grain formation during cogging forging of GH625 superalloy, isothermal hot compression tests were carried out on a Gleeble 3500 thermal simulator to investigate the high temperature deformation behavior of GH625 superalloy from 920 ℃ to 1190 ℃ and strain rate of 0.01 s^-1-10 s^-1. Based on the Arrhenius constitutive model, the constitutive equation of GH625 superalloy was established, which provided a theoretical basis for the simulation of the subsequent forging process. The results show that the flow stress increases sharply with the increase of strain, decreases slowly after reaching the peak value, and finally becomes stable. This change reflects the comprehensive effect of work hardening and dynamic recrystallization softening during deformation