Inclusion Criteria  Informed consent (radiation, medication) before treatment; Age 18 to 70 years old,regardless of gender; Initial SCLC confirmed by histopathological or cytological examination; Metastatic lesions in the distant area: included liver metastasis； Physical status score ECOG: 0 to 2； The expected survival time is more than 3 months; Bone marrow function:hemoglobin(HGB)>90g/L,platelet(PLT)>100×109/L,neutrophil cell(WBC)>1.5×109/L(*normal value); Liver function:alanine aminotransferase(ALT) and aspertate aminotransferase(AST)<1.5 times of the upper limit of normal(ULN);Total bilirubin <1.5ULN; Renal function:Serum creatinine was lower than 1.5ULN,and the endogenous creatinine clearance rate(Ccr) is higher than 55mL/min; Initial treatment (previously did not receive any thoracic radiotherapy or surgery).  Exclusion Criteria:  patients with history of mental illness; patients combined with other malignancies; Active period of disease caused by bacteria, fungi or viruses; and these severe infection requiring intravenous antibiotics,antifungal or antiviral therapy; Patients with serious cardiovascular disease ,including uncontrolled hypertension, unstable angina,history of myocardial infarction within the past 12 months,and severe arrhythmias. Patients with poorly controlled diabetes who are judged to be unfit for chemotherapy by doctors. History of hepatitis and cirrhosisi ; pregnant, lactating patients; Patients with poor compliance； Researchers believe that it is not appropriate to participate in this test.