This single-arm, Phase II study was designed to evaluate the safety and efficacy of Camrelizumab (anti-programmed death-receptor 1 [PD-1] antibody) combination with Apatinib in participants with ES-SCLC who was response or stable disease after firstline standard chemotherapy. Participants will be receive camrelizumab +apatinib on 21-day cycles until progressive disease (PD) as assessed by the investigator using Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST v1.1). Treatment can be continued until persistent radiographic PD or symptomatic deterioration.

Inclusion Criteria:

• Male or female patients aged 18 and 75 years old;
• Signed the informed consent form prior to patient entry;
• Eastern Cooperative Oncology Group performance status of 0 or 1;
• Expected Survival Time: Over 3 months;
• Pathological or cytologically proven extensive-Stage small cell lung cancer(according to Veterans Administration Lung Study Group)and without progression after Cycles 4-6 21-day cycles of first-line Standard chemotherapy(Evaluation was CR /PR/SD based on RECIST1.1);
• If prophylactic cranial irradiation (PCI) was not planned,informed consent was required to be written between 3 weeks and 5 weeks after day 1 of the last cycle of chemotherapy. If PCI was planned or already performe, informed consent was required to be written between 3 weeks and 8 weeks after day 1 of the last cycle of chemotherapy.

Exclusion Criteria:

• Has prior therapy with anti-programmed cell death (PD)-1, anti-PD-L1,anti Cytotoxic T lymphocyte-associated Antigen(CTLA)-4 or other Drugs that target T cells;
• Has prior therapy with angiogenesis inhibitors,Such as sunitinib, bevacizumab, apatinib, anlotinib;
• Has active or untreated central nervous system (CNS) metastases and/or cancerous meningitis;
• Imaging (CT or MRI) shows that tumor invades large blood vessels or the boundary with blood vessels is unclear;
• Has spinal cord compression which was not cured or relieved through surgery and/or radiotherapy, or diagnosed spinal cord compression after treatment showed no clinical evidence of disease stabilization prior to allocation ≥1 week;
• Within the past 2 weeks have used high dose antibiotics;
• According to the judgement of the researchers, there are other factors that may lead to the termination of the study.