Abstract: In order to investigate the effects of stevia isochlorogenic salt on performances, immune and serum hormone indexes of laying hens in late laying period, a total of 720 healthy 450-day-old Hy-line grey laying hens with similar performance were randomly divided into 4 groups with 6 replicates in per group and 30 hens per replicate: control group and high, medium and low dose groups. The animals in the control group were fed a basal diet, and the animals in the high-dose, medium-dose and low-dose groups were fed the basal diet supplemented with 400, 200, 100 mg/kg stevia isochlorogenic salt, respectively. The pre-trial period lasted for 7 days and the formal trial period lasted for 56 days. After the experiment, the performance indexes（laying rate, broken egg rate, blood shell egg rate, sand shell egg rate, eggshell thickness, average egg weight, average daily feed intake, and feed to egg ratio） of laying hens were determined. At the end of the experiment, 3 laying hens were randomly selected from each replicate and dissected after blood collection. Serum immune indexes（tumor necrosis factorα TNF-α, interferon γ IFN-γ, interleukin-6 IL-6, interleukin-8 IL-8, interleukin-10 IL-10, immunoglobulin G IgG, immunoglobulin M IgM）, hormone indicators（serum estradiol E2, follicle-stimulating hormone FSH, luteinosis hormone LH, thyroxine T4, triiodothyronine T3） and ovarian index were detected. The results showed as follows: compared with the control group, the laying rate and eggshell thickness in the high, medium and low dose groups were significantly increased（P＜0.05）, while the sand shell egg rate and broken egg rate were significantly decreased（P＜0.05）, and the average daily feed intake was not significantly different（P＞0.05）. Compared with the control group, the blood shell egg rate in the high and medium dose groups, the feed to egg ratio in the medium dose group, the mass concentrations of serum TNF-α, IFN-γ, IL-8, IgM and IgG in the high, medium and low dose groups in laying hens, and the mass concentration of IL-6 in high-dose and medium-dose groups were significantly decreased（P＜0.05）, while the mass concentration of IL-10 and the concentrations of E₂ in the high, medium and low dose groups were significantly increased（P＜0.05）, but the activities of FSH and LH and the concentrations of T4 and T3 were not significantly different（P＞0.05）. Compared with the control group, the ovarian index in the high, medium and low dose groups was increased by 9.35%, 15.11% and 6.11%, respectively. The results indicated that adding stevia isochlorogenic salt to the diet could improve the performances, egg quality and immunity of laying hens in late laying period. The optimal dosage was 200 mg/kg.