Hot deformation behavior of a novel Ni-Cr-Mo-B heavy plate steel was studied by hot compression tests,which were conducted on a Gleeble-3800thermo-mechanical simulator corresponding to the temperature range of850-1 150℃ with the strain rates of 0.01-10s-1 and the true strain of 0.8.The results suggest that the majority of flow curves exhibit a typical dynamic recrystallization(DRX)behavior with an apparent single peak stress followed by agradual fall towards a steady-state stress.Important characteristic parameters of flow behavior as critical stress/strain for initiation of DRX and peak and steady-state stress/strain were derived from curves of strain hardening rate versus stress and stress versus strain,respectively.Material constants of the investigated steel were determined based on Arrhenius-type constitutive equation,and then the peak stress was predicted by the equation with the hot deformation activation energy of 379 139J/mol,and the predicted values agree well with the experimental values.Furthermore,the effect of Zener-Hollomon parameter on the characteristic points of flow curves was studied using the power law relation,and the ratio of critical stress and strain to peak stress and strain were found to be 0.91and0.46,respectively. Hot deformation behavior of a novel Ni-Cr-Mo-B heavy plate steel was studied by hot compression tests, which were conducted on a Gleeble-3800thermo-mechanical simulator corresponding to the temperature range of 850-150 ° C with the strain rates of 0.01 -10s-1 and the true strain of 0.8. The results suggest that the majority of flow curves exhibit a typical dynamic recrystallization (DRX) behavior with an apparent single peak stress followed by agradual fall towards a steady-state stress. Imposing of characteristic parameters of flow behavior as critical stress / strain for initiation of DRX and peak and steady-state stress / strain were derived from curves of strain hardening rate versus stress and stress versus strain, respectively. Structural constants of the observed steel were determined based on Arrhenius-type constitutive equation, and then the peak stress was predicted by the equation with the hot deformation activation energy of 379 139 J / mol, and the predicted values ​​agree well with the expe rimental values. Future’s, the effect of Zener-Hollomon parameter on the characteristic points of flow curves was studied using the power law relation, and the ratio of critical stress and strain to peak stress and strain were found to be 0.91 and 0.46, respectively .