Abstract: The current study investigated growth performance, nonspecific immunity of white shrimp (Litopenaeusvannamei) by supplementation of chitosan quaternary ammonium salt in diets with graded levels of 0.0% (control group), 0.05%, 0.10%, 0.15% and 0.20% chitosan quaternary ammonium salt. Each diet was randomly fed to four cages of white shrimp with initial average weight (3.820.34) g in 20 cages (2.5 m1.5 m1 m) for 8 weeks. The result showed that the chitosan quaternary ammonium salt addition significantly improved growth performance with the best effect of weight gain and SGR in 0.15% group. The activity of lysozyme, alkaline phosphatase and phenol oxidase were significantly increased in the 0.1%, 0.15% and 0.20% trial groups (P0.05). Chitosan quaternary ammonium salt effectively improved the ability of shrimp to resist the vibrio parahaemolytics's infection (P0.05) with the best performance in 0.15% trial group that is 33.24%. These data indicate that chitosan quaternary ammonium salt can significantly improve the growth performance and the ability resisting infection, and the optimum amount under current experimental condition is 0.15%.