Abstract: This study investigated the effects of increasing dietary vitamin C on serum lysozyme activity and antioxidant ability of tissues in silver pomfret (Pampus argenteus). The basal practical diet was formulated with fish meal and shrimp meal as protein sources, and fish oil as lipid source. There were three experimental diets containing ascorbic acid 104.21 mg·kg^-1 (C1), 455.33 mg·kg^-1 (C2) and 800.54 mg·kg^-1 (C3) respectively, and triplicate feeding by every diet group to the juvenile with initial average weight (6.18±0.15) g for 9 weeks. The results show that serum lysozyme activity increases with the increase of dietary vitamin C, and lysozyme activity of C3 diet group is significantly higher than those of C1 and C2 diet groups (P < 0.05). The superoxide dismutase (SOD) activities significantly increase with the increasing vitamin C supplementation (P < 0.05), but the degree of influence is different in various tissues. High dietary vitamin C also significantly promotes the total antioxidant ability (T-AOC) of tissues (P < 0.05).Vitamin C concentrations in liver and muscle significantly improve with increasing vitamin C supplementation, while the malonaldehyde (MDA) contents of tissues significantly reduce with the increase of dietary vitamin C. In conclusion, increasing dietary vitamin C (>455.33 mg·kg^-1) can significantly improve the serum lysozyme activity and tissue antioxidant ability, and reduce the tissue lipid peroxidation of silver pomfret.