The experiment was conducted to study the effects of vitamin B₂ (VB₂) on the growth performance, endocrine and antioxidant capacity of laying ducklings in cage. Two hundred and eighty  eight 1-day-old  Jinding ducklings with an average body weight of (43.13±1.19) g were randomly allotted to 6 groups with 6 replicates of 8 ducks in each replicate. The ducklings in six groups were fed basal diet with 0, 4, 6, 10, 20 and 50 mg/kg VB₂, respectively. The results showed that: compared with control group, (1) for the diet with 10 mg/kg VB₂, average daily gain (ADG) increased significantly (P<0.05) and feed∶gain (F∶G) decreased significantly (P<0.05); the activities of T-AOC, SOD, GSH-PX in serum and CAT, GSH-PX in liver increased significantly(P<0.05) for the diet with10~20 mg/kg VB₂, while the activities of MDA decreased significantly (P<0.05); (2) along with the increase of VB₂ levels, the antioxidant capacity and growth performance showed the trend of first increase and then decrease. In conclusion, the growth performance and antioxidant capacity of laying duckings could be improved by adding 10 mg/kg VB₂ to the diet. However, both a too and a too low level of vitamin B₂ could affect the performance and antioxidant capacity of laying ducklings in cage.