This study was designed to evaluate the effects of temperature and dietary vitamin C levels on serum immune and antioxidative indices in reserved laying ducks. Two hundred and sixteen Jinding ducks (12 weeks old) were chosen and randomly divided into 6 treatments which were exposed to the environment at (2±1) ℃ and (18±1) ℃, dietary vitamin C was added at 0, 200 and 800 mg/kg, respectively. The trial lasted for six weeks. The results showed as follows: 1) the content of vitamin C in serum was significantly decreased by 27.78% (P<0.05), while there were significant effects on the contents of CAT, T-AOC, MDA, IL-2, IgG, IgA, IgM, GH, Ins, IGF-Ⅰ, leptin, Cort, T3 and T4 (P<0.05) in the situation of cold stress; 2) the levels of serum vitamin C, IGF-Ⅰ and leptin were increased (P<0.05) and Cort level was significantly decreased (P<0.05) by 200 mg/kg vitamin C supplementation; 3) the interaction of temperature and vitamin C significantly affected the contents of Cort (P＜0.01) and IGF-Ⅰ, leptin, IgG and IgA (P<0.05), there were no significant effects on GH, Ins, vitamin C, T3, T4 and antioxidant indices (P>0.05). It was concluded that the ability of vitamin C biosynthesis was influenced by low temperature, the contents of serum vitamin C, leptin, IGF-I and the ability of antioxidant and anti-cold stress were improved when adding 200 mg/kg vitamin C.［Chinese Journal of Animal Nutrition, 2010，22（4）:923-928］