This experiment was conducted to study the effects of dietary zinc level on growth performance, antioxidant function, and immune organ development of caged egg-type ducklings. Using a single factor completely randomized design, a total of 180 one-day-old Jinding egg-type ducklings were randomly divided into 5 groups with 6 replicates per group and 6 ducks in each replicate. Ducks in control group (group Ⅰ) were fed a basal diet, and the others in experimental groups (groups Ⅱ-Ⅴ) were fed the basal diet supplemented with 20, 40, 60 and 80 zinc (as ZnSO₄·7H₂O), respectively. The experiment lasted for 4 weeks. The results showed as follows: 1) the feed to gain in groups Ⅲ, Ⅳ and average daily gain in group Ⅲ were significantly higher than those in the control group (P<0.05). The average daily gain and feed to gain were changed quadratically with increasing dietary zinc level, and the estimation values of optimal dietary zinc level were 50.4 and 54.7 mg/kg, respectively. 2) The serum and liver total anti-oxidation capability (T-AOC), serum Cu-Zn-superoxide dismutase (CuZn-SOD) activity, liver malondialdehyd (MDA) content, and liver glutathion peroxidase (GSH-Px) activity in group Ⅲ had significant differences compared with the control group (P<0.05), and the estimation values of optimal dietary zinc level were 44.6, 47.8, 55.7, 43.4 and 54.2 mg/kg, respectively, but the serum MDA content, serum GSH-Px activity, and liver CuZn-SOD activity in group Ⅲ had no significant difference compared with the control group (P>0.05). 3) The thymus index, spleen index and bursa of Fabricius index in group Ⅲ were significantly higher than those in the control group (P<0.05). In conclusion, the optimal dietary zinc level of caged egg-type ducklings fed corn-soybean meal basal diet (33.3 mg/kg zinc) is 55.7 mg/kg.