Abstract: Head and neck squamous cell carcinoma (HNSCC) is a kind of malignant tumor characterized by metastasis and local invasion. Its recurrence rate is high after surgery and radiotherapy, and the prognosis and quality of life are poor. In recent years, programmed death- 1 (PD-1) inhibitors have been recommended in National Comprehensive Cancer Network (NCCN) guidelines for the treatment of recurrent, unresectable, and metastatic HNSCC, and their efficacy has been remarkable. PD-1 inhibitors constitute a new treatment for the patients with advanced HNSCC who are refractory to platinum-based chemotherapy and can increase the probability of surgical resection, reduce the risk of postoperative dysfunction, and improve the survival and quality of life. This article reviews the structure and mechanism of the PD-1/PD-L1 immunocheckpoint, as well as research progress on its inhibitors in the treatment of HNSCC.