Abstract: In this experiment, 216healthy Chinese perch (Siniperca chuatsi) with an initial weight of (37.26±0.22) g were selected and randomly divided into six treatment groups. Each group was fed an experimental diet containing different leucine levels of 1.88%, 2.49%, 3.13%, 3.73%, 4.29%, and 4.90%, designated as L1.88, L2.49, L3.13, L3.73, L4.29 and L4.90 for 8 weeks. The experimental results showed that the hepatosomatic and viscerosomatic indices of Siniperca chuatsi were linearly positively correlated with dietary leucine levels. The highest weight gain rate and specific growth rate were observed in the L3.13 group, while both indices were significantly lower in the leucine-deficient group (L1.88) and excess group (L4.90) groups compared to the other groups (P<0.05). In addition, the feed conversion rate of L3.13 group was significantly lower than those of other groups except for L3.73 group (P<0.05). With the increase in Leu levels, the overall trends of crude protein and crude fat in whole fish first increased and then decreased. The crude fat content in the L3.13, L3.73, and L4.29 groups was significantly higher than that of the other groups (P<0.05). The hepatic crude protein of the L3.19 and L4.90 groups was significantly lower than that of the L3.13 group. With the increase of leucine level, the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in liver were firstly increased and then decreased, and both were the lowest in the L1.88 group, while their activities in the L3.13 and L3.73 groups were significantly higher than those in other groups (P<0.05). Similarly, serum lysozyme (LYZ) and complement 3 (C3) in L3.13 and L3.73 groups were significantly higher than those of other groups (P<0.05). The activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST)decreased first and then increased with the increase of leucine content as well. ALT activity was the lowest in L3.13 group and the AST activity was the lowest in L3.73 group. Conversely, AST activity in L1.88 group was significantly higher than that in other groups (P<0.05). The expressions of n f-κb-p65 and tnf-α in L3.13 and L3.73 groups were significantly lower than those in other groups (P<0.05). The expressions of pai and il-1β in L3.13, L3.73 and L4.29 groups were significantly lower than that in other groups (P<0.05). The degree of vacuolation in liver cells of the L3.13 and L3.73 groups was significantly lower than that in the other groups, which is consistent with the trends in serum ALT and AST levels and the expression of immune genes. The results show that suitable dietary leucine levels can significantly improve feed efficiency, protein deposition, liver health, and nonspecific immunity of Siniperca chuatsi. However, excessive or insufficient leucine level is detrimental to the growth and immunity. In addition, quadratic regression analysis based on weight gain rate estimated the optimal dietary leucine level for juvenile Siniperca chuatsi to be 3.28%, accounting for 6.92% of protein level. This study provide a theoretical basis for feed formulation and breeding strategies for Siniperca chuatsi.