Background　　Worldwide lung cancer is the main cause of cancer related death .Small cell lung cancer accounts for about 15 to 20 percent of newly diagnosed patients with primary lung cancer. Small cell lung cancer used to be one of the most aggressive kinds of cancer and more than 60％ of the patients were presented with advanced disease when they were diagnosed. Thoracic radiation therapy is one of the treatment modality for extensive stage small cell lung cancer patients.　　To check whether the addition of thoracic radiotherapy to systemic chemotherapy will improves the one-year and two-years survival in patients with extensive stage small cell lung cancer, a comprehensive meta-analysis was performed.　　Methods　　A comprehensive search of Science Direct, Pubmed, Embase, Wanfang Data from 1982 to 2012 was done and the studies met the following criteria were included in this meta analysis:(1) all patients have extensive-stage small cell lung cancer, (2) comparing two groups, one receiving thoracic radiation therapy combined with chemotherapy and the other group receiving only chemotherapy, (3) one-year and 2-years overall survival data were provided. Pooled relative risk (RR) and risk difference (RD) were calculated, publications bias was evaluated and sensitivity analysis was conducted.　　Results　　Ten studies meeting the inclusion criteria were identified enrolling 922 patients, 534 patients were in the chemotherapy combined with thoracic radiation therapy group (ChT/TRT) and 388 patients were in the chemotherapy group (ChT).In this meta analysis I found that addition of thoracic radiation therapy to chemotherapy increases the one year overall survival rate to 52% as compared to 32.2% when using chemotherapy alone, the two years survival of 18.7%also increased as compared to 10%when using chemotherapy alone.For 1-year overall survival, the ChT/TRT group was significantly better than the ChT group, the pooled RR was 1.61 for ChT/TRT group compared to ChT group (95%CI,1.36-1.90,P<0.00001) and the pooled RD was 0.2 for ChT/TRT group compared to ChT group(95%CI,0.13-0.26,P<0.00001).For 2-years overall survival, the ChT/TRT group was significantly better compared to ChT group, the pooled RR was 1.90 for ChT/TRT group compared to ChT group (95%CI,1.34-2.68,P=0.0003) and the pooled RD was 0.09 for ChT/TRT group compared to ChT group(95%CI,0.05-0.13,P<0.0001)　　Conclusion　　The findings in this study shows that the addition of thoracic radiation therapy to chemotherapy improves both 1-year and 2-years survival in patients with extensive-stage small cell lung cancer.