Objective To analyze the incidence and risk factors of hypothyroidism in patients with naso⁃ pharyngeal carcinoma after receiving radiotherapy and sequential immunotherapy. Methods A total of 66 patients with nasopharyngeal carcinoma who had undergone radiotherapy and immunotherapy were enrolled. According to present or absent of hypothyroidism，the patients were divided into hypothyroidism group and non⁃hypothyroidism group. Changes in the incidence of hypothyroidism were analyzed after the combined treatment. Multivariate logistic regression analysis was used to screen the independent risk factors of hypothyroidism in the patients receiving radio⁃ therapy and immunotherapy. Results The median follow⁃up time was 12 months in 66 patients. 18 patients（27.3%） developed hypothyroidism at various degrees. The median time was 19.5 months from the end of radiotherapy and 3 months from the beginning of immunotherapy. The incidence of hypothyroidism after radiotherapy combined with sequential immunotherapy for nasopharyngeal carcinoma was higher than that in the patients undergoing radiotherapy or immunotherapy alone. Multivariate logistic regression analysis showed present or absent of thyroid nodules（P = 0.046）and baseline LDH（P = 0.047）were independent risk factors of hypothyroidism after radiotherapy in combi⁃ nation with sequential immunotherapy for nasopharyngeal carcinoma. The area under the ROC curve（AUC）was 0.853. Conclusions After intensity⁃modulated radiotherapy and sequential anti⁃PD⁃1 immunotherapy for nasopha⁃ ryngeal carcinoma，the incidence of hypothyroidism increased significantly. For the patients with nasopharyngeal carcinoma who had thyroid nodules or an increase in baseline LDH level，the risk of hypothyroidism occurrence was markedly elevated after radiotherapy and sequential immunotherapy.