Abstract: Homogenized GH4251 alloy specimens were taken as research objects, and single-pass isothermal hot compression tests were carried out. A constitutive flow stress model considering the effect of temperature-compensated strain rate was established based on the Arrhenius hyperbolic sine function. The Poliak-Jonas method was employed to quantitatively characterize the critical conditions of dynamic recrystallization for GH4251 alloy. The results show that an increasing trend with lower deformation temperatures and higher strain rates, while a stable and good linear correlation exists between critical DRX(dynamic recrystallization) strain and peak strain. The thermo-mechanical coupled constitutive modelestablished in the study can support die-forging process simulations for GH4251 components and provide a theoretical basis for elucidating DRX mechanisms in highly alloyed difficult-to-deform Ni-based superalloys.