A feeding trial was conducted to determine the dietary copper(Cu)requirement and its effect on hemocye phenoloxidase(PO)and superoxidedismutase(SOD)activities of the Litopenaeus vannamei.Results showed the activities of PO and SOD were higher as shrimp fed diets supplemented with 30~45mg Cu/kg diet than any other diet.When a little bit more Cu added to the diet,its effect on activity of SOD was much more significantly than that on activity of PO.