Abstract: [Objective] The aim was to investigate the effects of different doses of cysteamine （CS） on the production performance and hormone levels of hens during late laying period to find out the most appropriate adding dose. [Method] 576 43-week old broilers from the same source were randomly divided into 6 treatments （n=96） with 3 replicates, among them group Ⅰ , as the control group, was provided with basic diet, while group Ⅱ,Ⅲ, Ⅳ,Ⅵ and Ⅵwere fed with basic diet supplemented with cysteamine at the level of 100, 150, 200, 250 and 300 mg/kg, respectively. The experimental period was 21 days, and the laying rate, ratio of feed to egg and hormone levels of serum were detected on the 1~, 8a, 15~ and 22~ day. [Result] The cysteamine degraded the ratio of feed to egg, raised the laying rate, and eased the slump of the estrogen level. [Conclusion] Cysteamine can relieve the fall of production performance and estrogen level of hens during late laying period.