Head and neck cancer is one of the common malignant tumors，and most patients are diagnosed in the middle or late stages of the disease. Therefore，early diagnosis，accurate staging，and efficacy monitoring are the key to optimizing treatment strategies and improving prognosis of head and neck cancer. Integrated positron emission tomography/magnetic resonance imaging（PET/MRI） combines molecular function and anatomical structure imaging，harnessing the complementary advantages of PET and MRI. By combining the metabolic information of PET with the excellent soft tissue contrast of MRI，it truly achieves multimodal imaging，which is of significant clinical importance in the diagnosis，treatment，and monitoring of tumors. This review mainly focuses on the application and progress of PET/MRI in the diagnosis，staging，monitoring of efficacy，prognosis prediction，and development of radiotherapy plans for head and neck cancer.