Abstract: In order to investigate the effects of different stocking density on the immune parameters and growth of juvenile Litopenaeus vannamei, we cultured the shrimps body length (3.59±0.26) cm in 0.3 m³ fiberglass tanks (water volume 0.5 m³) at 1 800 ind·m^-3, 1 500 ind·m^-3 and 1 200 ind·m^-3, respectively, for 30 d to determine the phenoloxidase (PO) activity, superoxide dismutase (SOD) activity, antibacterial activity (Ua), alkaline phosphatase (AKP) activity in hepatopancreas and muscle, as well as weight gain, survival and basic water quality factors. It is showed that the physical and chemical factors vary within suitable range with no significant difference. The PO activity, Ua and AKP activity in the muscle of shrimp reduce while SOD activity increases with the increase of stocking density. The weight gain, special weight growth rate (SGR_w) and survival reduce with the increasing stocking density with significant difference in survival (P < 0.05). The results indicate that stocking density may obivously affect the growth and immune parameters of juvenile L.vannamei (body length < 4.8 cm or body weight < 1.2 g) when stocking density is within 1 200~1 800 ind·m^-3.