Abstract: This study aimed to investigate the effects of dietary protein level on growth performance, intestinal histology, antioxidant and immune capacity of largemouth bass (Micropterus salmoides) larvae. Five isolipidic experimental diets were formulated with crude protein contents of 45% (CP45), 48% (CP48), 51% (CP51), 54% (CP54) and 57% (CP57), respectively. Healthy M. salmoides larvae with an initial body weight of (1.25±0.00) mg were randomly divided into 5 groups with 3 replicates per group and 7 500 larvae per replicate, and the feeding trial lasted for 21 days. The results showed that with increasing dietary protein content, the final biomass and survival rate of M. salmoides larvae increased first and then decreased (P < 0.05); the final biomass in the CP54 group was significantly higher than that in all other groups (P < 0.05), and the final biomass in the CP51 and CP57 groups was significantly higher than that in the CP45 and CP48 groups (P < 0.05); the survival rate in the CP51, CP54 and CP57 groups was significantly higher than that in the CP45 and CP48 groups (P < 0.05), while no significant differences were found in final body weight, weight gain rate and specific growth rate among all groups (P > 0.05). The optimal dietary protein level for M. salmoides larvae determined on the basis of survival rate and final biomass was 54.80%-55.25%. There were no significant differences in intestinal villus height, villus width and muscle layer thickness among all groups (P > 0.05). The malondialdehyde (MDA) content in the CP51, CP54 and CP57 groups was significantly lower than that in the CP45 group (P < 0.05), and the MDA content in the CP51 and CP57 groups was significantly lower than that in the CP48 group (P < 0.05). There were no significant differences in the activities of catalase, total superoxide dismutase (T-SOD), alkaline phosphatase and acid phosphatase among all treatments, whereas T-SOD activity exhibited an increasing trend with the elevation of dietary protein level (P = 0.07), and the optimal dietary protein level was determined to be 51.00%-55.16% according to MDA content and T-SOD activity. Under the water temperature of 20-24 ℃, larvae fed with optimal dietary protein levels presented higher survival rate, final biomass and antioxidant capacity, and the suitable dietary protein level for M. salmoides larvae was 54.80%-55.25% to achieve the best survival and final biomass. These results provide a scientific theoretical basis for the development and precise preparation of special compound feeds for M. salmoides larvae during artificial seedling cultivation, and exert an important guiding function in improving seedling survival rate and optimizing aquaculture production efficiency.