This study was designed to evaluate the effects of vitamin A (VA) on immune function and correlated hormone secretion in growing laying ducks. Two hundred and sixteen  Jinding  ducks with an average body weight of (0.37±0.01) kg were chosen and randomly divided into 6 groups with 6 replicates of 6 ducks in each replicate. Ducks in six groups were fed basal diet with supplements of 0, 2 250, 5 500, 8 250, 12 000, 15 000 IU/kg VA, respectively. The trial lasted for 7 weeks. The result showed that compared with control group, the weight and indices of thymus and bursal were not influenced by different levels of VA (P>0.05), spleen and spleen indices increased significantly in 5 500 IU/kg VA group (P<0.05). The ALB increased significantly by adding different levels of VA (P<0.05), the GLB significantly or extremely significantly increased when VA supplemental levels were 5 500, 8 250, 12 000 and 15 000 IU/kg (P<0.05 or P<0.01). There were no significant differences among the groups in IgG, IgM and IL-2 (P>0.05). The content of T₃, T₄ first increased and then decreased as the level of VA increased (P>0.05), and the highest group was 8 250 IU/kg VA group. The GH content in 15 000 IU/kg VA group was much lower than those in the control group and the 8 520 IU/kg VA group (P<0.05). It was concluded that adding 5 500～8 250 IU/kg VA to the diet could improve immune function and regulate correlated hormone secretion of growing laying ducks.