Protein requirements are affected by the growth stage. Generally, early-life-stage crayfish usually have higher protein requirements. An 8-week experiment was performed to investigate the effects of different dietary protein levels on growth performance, body composition and antioxidant capacity of Procambarus clarkii at three different growth stages. ① With the increase in dietary protein level, WGR and SGR of crayfish was first increased and then stabilized in the three different growth stages. ② With the increase in dietary protein level, the FCR was first decrease and then stability. ③ In the first and second growth stage, the crude protein was first increased and then stabilized; in the third growth stage, the lowest crude protein content was observed in the group fed with 250 g/kg dietary protein. ④ With the increase in dietary protein level, both the superoxidase dismutase (SOD) activity and the phenoloxidase (PO) activity were increase in the first and second growth stage; in the third growth stage, after the dietary protein levels exceeded 300 g/kg, both the superoxidase dismutase (SOD) activity and the phenoloxidase (PO) activity were decrease. Based on these findings and a broken-line model of specific growth rate, 403.3 g/kg, 358.8 g/kg and 305.6 g/kg were determined to be the optimal diet protein levels for the crayfish with initial body weight of 0.026 g, 1.04 g and 5.06 g, respectively.