To evaluates the effectiveness and safety of Surufatinib combined with chemotherapy plus Toripalimab or not for the first-line treatment of SCLC, and maintenance therapy are Surufatinib combined with Toripalimab or not.

Inclusion Criteria:

1. Patients must have the ability to understand and voluntarily sign informed consent;
2. Age: ≥18 years old;
3. Expected survival period ≥ 3 months;
4. Adavanced small cell lung cancer confirmed by histology ;
5. According to the RECIST 1.1 standard, the patient has at least one target lesion with a measurable diameter;
6. ECOG PS: 0-1;
7. Laboratory test indicators must meet the following requirements: Hematology: white blood cells ≥4.0×10^9/L, neutrophils ≥2.0×10^9/L, platelet count ≥100×10^9/L, hemoglobin ≥90g/L. Liver function: serum bilirubin is lower than 1.5 times the maximum normal value; for patients without liver metastasis: ALT and AST are lower than 2.5 times the maximum normal value; for patients with liver metastasis: ALT and AST are lower than 5 times the maximum normal value ; Measured or calculated creatinine clearance: According to the Cockcroft-Gault formula (using actual body weight), patients receiving cisplatin treatment>60mL/min, and patients receiving carboplatin treatment>45mL/min;
8. Good compliance and follow-up;
9. The urine or serum pregnancy test results of premenopausal women were negative.

Exclusion Criteria:

1. Patients with symptomatic brain metastases;
2. People with hypertension who cannot be well controlled by double antihypertensive drug (systolic blood pressure≥140 mmHg, diastolic blood pressure≥90 mmHg);
3. Urine routine test showed urine protein ≥+++ and confirmed 24-hour urine protein quantification>3.0g;

5.Cardiovascular disease history: congestive heart failure> New York Heart Association (NYHA) standard II, patients with active coronary artery disease (those with myocardial infarction 6 months before enrollment can be enrolled), arrhythmia requiring treatment (Allows to take beta blockers or digoxin); 6.Active severe clinical infections (>NCI-CTCAE 5.0 version 2 infection criteria), including tuberculosis (clinical evaluation, including clinical history, physical examination, imaging findings and TB examination in line with local clinical practice), hepatitis B (known HBV Surface antigen [HbsAg] positive), hepatitis C or human immunodeficiency virus (HIV 1/2 antibody positive). Patients who have previously had HBV infection or have been cured (defined as the presence of hepatitis B core IgG antibodies and the absence of HBsAg) are eligible. Hepatitis C virus (HCV) antibody-positive patients are only eligible if the HCV RNA polymerase chain reaction is negative; 7.Patients with bleeding tendency or coagulation disorders, (14 days before randomization must meet: INR is within the normal range without the use of anticoagulants); 8.In the past 2 years, there are active autoimmune diseases that require systemic treatment (such as corticosteroids or immunosuppressive drugs), and related alternative treatments (such as thyroxine, insulin, or physiological corticosteroid replacement for renal or pituitary insufficiency) are allowed treatment); 9.Those who have received live vaccination within 4 weeks before the start of treatment; 10.Those who had suffered from tumors other than small cell lung cancer within 5 years before being enrolled in this study. Except: cervical carcinoma in situ, cured basal cell carcinoma, cured bladder epithelial tumor; 11.Severe unhealed wounds, ulcers or fractures; 12.Patients who are pregnant or breastfeeding ; 13.Any unstable conditions may endanger the safety of patients and affect their compliance with research; 14.Researchers think it is inappropriate to participate in this trial.