One-day-old healthy ducklings (n = 100) were randomly allocated into two groups (n =50, respectively) to investigate the effect of cytokines on ducklings with selenium poisoning. The ducklings in control group (Group Ⅰ) were fed with full rations containing 0.3 mg kg-1 selenium, and the ducklings in selenium poisoning group (Group Ⅱ) were fed with selenium-excessive rations containing 8.0 mg kg-1 selenium. One mL blood was collected by cardiac puncture at d 15, 30, 60, and 90(n = 10, respectively), serum was separated by centrifugation. Contents of cytokines were determined by the radio-immunity method (RIA). The results showed that the contents of IL-1 β, IL-2β in Group Ⅱ were higher than that in control group at d 15 (P＞0.05), but were significantly lower at d 30, 60, and 90 (P＜0.01); the contents of IL-8β in Group Ⅱ were significantly lower than that in control group (P＜0.01); the contents of erythropoietin (EPO) and IGF-2 in Group Ⅱ were significantly lower in different degree than that in control group at d 60 and 90 (P ＜ 0.01); the contents of granulocytemacrophage colony stimulating factor (GM-CSF) in the two groups were lower in different degree and significantly lower at d 60 and 90 (P＜0.01). It can be concluded that the excessive selenium could result in a decrease in immunity and a series of clinical pathology changes, such as anemia, tissue hemorrhage, and necrosis.