Although fist-line therapy with Cisplatin and etoposide(EP)or Carboplatin and etoposide(CE) has been given,patients with extensive small cell lung cancer(ED-SCLC) still relapse and the 2-year survival is extremely low. There is no standard maintenance treatment recommendation for ED-SCLC patients after the first-line therapy.Apatinib has been approved as a second-line treatment for advanced gastric cancer. Several phase III clinical studies of non small cell lung cancer,liver cancer,colorectal cancer and other tumors also showed apatinib has less toxic side effects and better patient tolerance. However,the clinical application of apatinib in small cell lung cancer is still lack of evidence-based medicine,so this clinical trial is designed to investigate the efficacy and safety of apatinib combine with etoposide as maintenance therapy in ED-SCLC patients after first-line chemotherapy in our center.