Abstract: Inconel 625 Ni-based superalloy was heated to 1 050, 1 150 ℃ for 1.5 h, respectively, forged under forging energy of 16 kJ, and water quenched. The deformation amount, grain size and forging force were measured. Theoretical deformation amounts of the alloy were calculated by definition and slice methods, respectively. Grain size of the alloy was simulated by finite element forging model. The calculation and simulation were compared with experiments. The results show that the deformation amount of the tested alloy was 17 mm at 1 150 ℃, about 2 mm larger than that at 1 050 ℃, and the maximum forging force was lower than that at 1 050 ℃. The relative error between theoretical deformation amount and the experiment was about 5%, indicating that both the definition method and slice method can predict deformation amounts accurately. By simulation, the grain size of the alloy when heating to 1 150 ℃ was obviously higher than that when heating to 1 050 ℃. After heating to 1 150 ℃, forging and quenching, relative errors of the simulated grain size number in surface and core with the experiments were below 10%; the simulation was relatively accurate.