Inclusion Criteria:  Newly diagnosed recurrent or metastatic head and neck squamous cell carcinoma which is histologically or cytologically confirmed, and unable to be cured by local treatment (the primary site of the tumor is the oropharynx, oral cavity, hypopharynx and larynx), recurrence or metastasis stage did not receive any anti-tumor systemic therapy (allowed as part of the treatment of locally advanced tumors, and it has been more than 6 months from the end of treatment to signing the informed consent); ECOG score of 0 or 1; At least one measurable lesion according to RECIST1.1 criteria. Tumor tissue with PD-L1 detection (paraffin specimens or fresh tumor tissue within 2 years) can be provided; Patients with Oropharyngeal cancer should provide P16 detection status by using IHC method; Patients with a history of brain/meningeal metastasis must be treated with local therapy (surgery/radiotherapy) before the start of the study, and clinically stable for at least 3 months (corticosteroids are allowed before the first dose of the study drug, but need to be discontinued 2 weeks before the start of the study drug); The subjects voluntarily joined the study, signed the informed consent form, had good compliance, and cooperated with the follow-up.  Exclusion Criteria:  Progression within 6 months after systemic treatment for locally advanced head and neck squamous cell carcinoma; Previous history of primary tumor of nasopharyngeal carcinoma; Intolerable to platinum-based therapy; Previous treatment with platinum-based regimen and disease progression; Patients who participated in or were participating in other drug/therapy clinical trials 4 weeks before the first dose of study drug; Patients who underwent major surgery or had not recovered from the side effects of this surgery; Patients who has accepted live vaccination, immunotherapy, or patients who underwent radiotherapy within 2 weeks; Patients who received any other anti-tumor treatment; Patients who are using immunosuppressive agents, or systemic hormone therapy to achieve the purpose of immunosuppression (dose > 10 mg/day prednisone or other effective hormones), and continue to use 2 times before enrollment; History of other malignant tumors within the past 5 years, except cured cutaneous basal cell carcinoma, cutaneous squamous cell carcinoma, early prostate cancer and cervical carcinoma in situ; Patients who have received hematopoietic stimulating factors, such as granulocyte colony-stimulating factor (G-CSF), erythropoietin and other treatments before the first dose of study drug; Prior treatment with PD-1/PD-L1/PD-L2/CTLA-4 antibodies or activating or inhibiting drugs against T cell receptors (e.g., OX40, CD137); Presence of active or uncontrolled metastatic central nervous system tumor lesions diagnosed by imaging; Positive test results for HIV antibody or Treponema pallidum antibody; Known to be allergic to recombinant humanized PD-1 monoclonal antibody drugs and their components; Active pulmonary disease (interstitial pneumonia, pneumonia, obstructive pulmonary disease, asthma) or history of active pulmonary tuberculosis; Patients who have received re-radiotherapy in the head and neck position (including cervical, supraclavicular and subclavian lymph nodes) within 6 months before enrollment; Patients who have tumor encasement, invasion or infiltration of large blood vessels, invasion of the skin or mucosal cavity, or ulceration and bleeding of tumor lesions; Patients who have previously received VEGF/VEGFR-targeted anti-vascular drug therapy; Patients who are known to be allergic to Apatinib mesylate and any excipients of it; Patients who are suffering from hypertension, and cannot be well controlled by antihypertensive drug therapy (systolic blood pressure ≥ 140 mmHg or diastolic blood pressure ≥ 90 mmHg); Patients who have any condition affecting the swallowing of drugs by subjects, and any condition affecting the disposition process (absorption, distribution, metabolism or excretion) of the test drug in the body; Patients who have coagulation abnormalities (INR > 2.0, PT > 16 s), with bleeding tendency or receiving thrombolytic or anticoagulant therapy. Prophylactic use of low-dose aspirin, low-molecular-weight heparin is permitted. Patients who had clinically significant bleeding symptoms or clear bleeding tendency within 3 months before enrollment, such as pertussis/hemoptysis of 2.5ml or more, gastrointestinal bleeding, esophageal and gastric varices at risk of bleeding, hemorrhagic gastric ulcer or suffering from vasculitis, etc. Known inherited or acquired bleeding or thrombotic tendencies (e.g., hemophilia, coagulopathy, thrombocytopenia, etc.)