Due to their excellent properties, nickel-based superalloys are extensively used in critical parts of modern aero engine and gas turbine. The hot deformation behaviors of a typical nickel-based superalloy are investigated by hot compression tests with strain rate of (0.001-1) 1/s and forming temperature of (920-1040) oC. Results show that the flow stress is sensitive to the forming temperature and strain rate. With the increase of forming temperature or the decrease of strain rate, the flow stress decreases significantly. Under the high forming temperature and low strain rate, the flow stress-strain curves show the obvious dynamic recrystallization. Based on the stress-dislocation relation and kinetics of dynamic recrystallization, a two-stage constitutive model is developed to predict the flow stress of the studied nickel-based superalloy. Comparisons between the predicted and measured flow stress indicate that the established physically-based constitutive model can accurately characterize the hot deformation behaviors for the studied nickel-based superalloy.