(Objective)This study aimed to evaluate the effects of different stocking densities on the growth performance, growth uniformity, serum biochemical parameters, and immune-antioxidant indices of Litopenaeus vannamei cultured in a low-salinity recirculating aquaculture system, in order to determine the optimal stocking density.(Methods)The salinity of the culture water was maintained at (3.5 ± 0.5)‰. Juvenile shrimp with an average initial body weight of approximately 1.04 g were randomly assigned to five groups. Each 300-L tank was stocked with 30, 45, 60, 75, or 90 individuals, designated as M30, M45, M60, M75, and M90, respectively, with four replicates per treatment. The experiment lasted 49 days. (Results)As stocking density increased, FBL, DLGR, LGR, SGRL, FBW, DWGR, WGR, and SGR all showed significant decreasing trends (P< 0.05), with the lowest values observed in the M90 group. Survival rate (SR) was highest in the M60 group, significantly higher than in M75 and M90 (P< 0.05). Feed supply density (FSD) and yield increased significantly with density (P< 0.05). The hepatosomatic index (HSI) of M60 was significantly lower than those of M75 and M90 (P< 0.05). Coefficient of variation in length (CVL) was the lowest in M75, followed by M45, both significantly lower than M90 (P< 0.05), whereas length uniformity showed the opposite trend. Shrimp body length in all groups was mainly concentrated in the 10–12 cm range, but the peak body-weight distribution shifted toward lower weights as density increased. Feed intake (FI) decreased significantly with increasing density (P< 0.05). The feed conversion ratio (FCR) was lowest in M60 and significantly lower than that of M90 (P< 0.05). Both feed intake and feeding rate decreased significantly at higher densities (P< 0.05), with inhibitory effects more pronounced during the later stages. Except for TP and GLB, which were higher in M75 than in M30 (P< 0.05), no significant differences were observed in ALB, A/G, BUN, GLU, ALT, AST, ALP, or lipid-related indices. T-AOC was highest in M30, and LZM activity was highest in M45, both significantly greater than in M90 (P< 0.05). (Conclusion) Considering growth performance, feed utilization, and immune-antioxidant responses, a density of 60 individuals per 300 L (approximately 194 ind/m3) is recommended as the optimal stocking density for L. vannamei under low-salinity recirculating aquaculture conditions. These findings provide a theoretical basis for shrimp culture under low-salinity recirculating systems and hold practical reference value.