Objective：To explore clinical and immune function effect of spleen polypeptide injection combination with concurrent chemoradiotherapy in patients with limited-stage small cell lung cancer（LS-SCLC）. Methods：From January 2013 to January 2017，76 LS-SCLC patients were divided randomly into observation and control groups（38 patients in each）from the Affiliated Cancer Hospital of Nanjing Medical University. Control group were given concurrent chemoradiotherapy，and observation group were given the same therapy combined with spleen polypeptide injection. The clinical results，T cell and its subtypes，survival probabilities and adverse reactions were evaluated. Results：The improvement rates of Karnofsky performance score（KPS）in the observation group were significantly better than those in the control group（P < 0.05）. The observation and control groups had a similar response rate（84.2% and 89.5%，respectively）. When comparing hematologic toxicity，the observat group had a less incidence rate of leucopenia（60.5% vs. 84.2%，χ2＝5.33，P=0.04）. Compared with pre-treatment，the levels of CD3+，CD4+and CD4+/CD8+ in the observation group were increased and had significant differences（P < 0.05），whereas，the control group had no obviously increasing. The progress-free survival of observation group was significantly improved comparing with that in control group（P=0.03）. However，there was no statistic significance in the overall survival between two groups（P=0.22）. Conclusion：Spleen polypeptide injection can improve the activity of immune function and prolong PFS of the patients during the chemoradiotherapy for LS-SCLC.