Inclusion Criteria:  1. 18-70 years old, no gender limit; 2. Oligo metastasis is defined as less than or equal to 5 metastatic lesions and less than or equal to 2 metastatic organs 3. Patients with an ECOG score of 0 or 1, and an expected survival period of ≥6 months;  4. Has good organ function:  Hematology: WBC>3.0×109/L; ANC>1.5×109/L; Hb>90g/L; PLT>100×109/L; Albumin ≥3g/dL; Liver function: bilirubin ≤ 1.5 times the upper limit of normal (ULN) (patients with known Gilbert disease and serum bilirubin level ≤ 3 times ULN can be included), AST and ALT ≤ 3 times ULN (if liver metastases occur , Then AST/ALT≤5 times ULN), and alkaline phosphatase≤3 times ULN (if liver or bone metastasis occurs, ALP≤5 times ULN); （3） Coagulation function: International normalized ratio (INR) or prothrombin time (PT) or activated partial thromboplastin time (APTT) ≤ 1.5 times ULN; （4）Renal function: According to the Cockcroft-Gault formula (Appendix 8), serum creatinine ≤1.5 times ULN or creatinine clearance ≥60mL/min. 5. Female subjects have a negative pregnancy test (for female patients with fertility); female patients without fertility; 6. Male patients with fertility and female patients with fertility and risk of pregnancy must agree to take adequate contraceptive measures throughout the study period, and contraception lasts for 12 months after receiving this program. 7. Patients who are willing and able to comply with visit arrangements, treatment plans, laboratory tests and other research procedures; 8. During the research period, they are willing to comply with the arrangement and cannot participate in any other clinical research on drugs and medical devices; 9. For patients who have previously received neoadjuvant chemotherapy, adjuvant chemotherapy, radiotherapy or radiotherapy for non-metastatic diseases, the time from the last chemotherapy and/or radiotherapy to randomization must reach a non-treatment interval of ≥ 6 months . Oral S1 and capecitabine have no requirement for treatment interval for those who are progressing during chemotherapy. 10. The patients sign a formal informed consent form to show that they understand that this study complies with the hospital's policies  Exclusion Criteria:  1. Those who have a history of severe immediate hypersensitivity to any of the drugs used in this study; 2. Suffered from other malignant tumors other than nasopharyngeal carcinoma within 5 years (except for tumors with an expected 5-year OS>90%, such as non-melanoma skin cancer or pre-invasive cervical cancer); 3. Any of the following conditions in the 6 months before screening: myocardial infarction, severe/unstable angina, coronary artery/peripheral artery bypass graft, symptomatic congestive heart failure, cerebrovascular accident, transient cerebral ischemia Onset or symptomatic pulmonary embolism. Patients with known coronary artery disease, congestive heart failure that does not meet the above criteria, or left ventricular ejection fraction <50% must adopt an optimized and stable medical plan determined by the treating doctor. If appropriate, you can consult a cardiologist;  4. Have received any of the following treatments:  Have received anti-PD-1 or anti-PD-L1 antibody therapy in the past; Have received any investigational drug within 4 weeks before using the investigational drug for the first time; A large number of glucocorticoids or other immunosuppressants (including but not limited to prednisone, dexamethasone, azathioprine, methotrexate, thalidomide, and anti-tumor necrosis factor) have been used in the 4 weeks before treatment Subjects with anti-TNF drugs, or subjects in need of hormone therapy during clinical trials. Other special circumstances require communication with the sponsor. In the absence of active autoimmune diseases, inhaled or topical steroids and adrenal cortex hormones with a dose> 10 mg/day of prednisone are allowed to be substituted; Those who have been vaccinated with anti-tumor vaccines or the study drug has been vaccinated with live vaccines within 4 weeks before the first administration; Have undergone major surgery or severe trauma within 4 weeks before using the study drug for the first time; Enroll in another clinical study at the same time, unless it is an observational (non-interventional) clinical study or an interventional clinical study follow-up;  5. Patients with active autoimmune disease or a history of autoimmune disease but may relapse. Remarks: Patients with the following diseases are not excluded and can enter further screening:  Controlled type 1 diabetes Hypothyroidism (if only hormone replacement therapy can be used to control) Skin diseases that do not require systemic treatment (such as vitiligo, psoriasis, hair loss) Any other diseases that are not expected to recur without external triggers 6. Active infections, including tuberculosis, hepatitis B, hepatitis C and human immunodeficiency virus. Patients with positive HBV surface antigen (HBsAg) but HBV DNA <1000 copies/mL are eligible to participate in this study; patients with positive HCV antibody test results are only allowed if the HCV RNA polymerase chain reaction test results are negative. Be selected for this study; 7. Idiopathic pulmonary fibrosis, drug-induced pneumonia, organizing pneumonia (bronchiolitis obliterans), idiopathic pneumonia, or chest CT scan at the time of screening shows evidence of active pneumonia; 8. Drug abuse or alcohol addiction; 9. No capacity for civil conduct or limited capacity for civil conduct; 10. The patient has a physical or mental illness, and the researcher believes that the patient cannot fully or fully understand the possible complications of this study; 11. Other serious acute or chronic medical conditions (including immune colitis, inflammatory diseases, Enteropathy, non-infectious pneumonia, pulmonary fibrosis) or mental illness (including dementia and epilepsy, recent, past year or active suicidal ideation or behavior) or abnormal laboratory tests; 12. Patients whose expected survival time is less than 6 months; 13. Patients with significantly reduced heart, liver, lung, kidney and bone marrow functions 14. Previously diagnosed as immunodeficiency or known human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS) related diseases; 15. Female patients during pregnancy or lactation, male or female patients who are fertile but are unwilling or unable to use contraception during the entire study period and at least one year after the end of the treatment plan;