The studies were conducted to determine the effects of VC on the immune actors of the Chinese mittenhanded crabs Eriocheir sinensis［initial mean weight of (37.52±2.29) g］. The crabs were distributed into the glass tanks of 200 L capacity using a completely randomized design with five treatments espectively and each treatment was stocked with 10 crabs and was run in triplicate per treatment. The crabs E. sinensis were fed 60 d with a series of test diets containing graded levels of VC ［0, 250, 500, 1000, 1500 mg·(100g)-1 diet respectively］. Each treatment was run in triplicate. The activities of phenoloxidase (PO), antibacterial performance (Ua), lysozyme (UL), superoxide dismutase (SOD), alkaline phosphatase (AKP) and acid phosphatase (ACP) were measured. The results indicated that the effects of dietary VC on the activities of PO, Ua, UL, SOD, AKP and ACP in the tissues and organs of E. sinensis were significant difference (P<0.05 or P<0.01).The activities of PO, Ua, UL, AKP and ACP in the serum, muscle, hepatopanc rea and ovary of E. sinensis were significantly enhanced with V C supplement increasing in the range from mg·(100g)-1 diet to 1000 mg· (100g)-1diet (P<0.05 or P<0.01). However, the activities of AKP were declined at 1500 mg·(100g)-1 diet VC. The activities of SOD in the serum, muscle, hepatopancrea and ovary of E. sinensis were significantly lowered with VC supplementation. VC could promoting non-special immunity, improve animal health, enhancing general metabolism of E. sinensis, and optimum supplementation of VC to increase nonspecific immunity in E. sinensis was 500-1000 mg·(100g)-1 diet VC. The study also revealed the relationship of the activities of enzymes and non-special immunity of E. sinensis.