Objective To investigate the characteristics of symptom burden and extract symptom clusters in lung cancer patients at the end of thoracic radiotherapy.Methods Lung cancer patients receiving Thoracic Radiotherapy were collected from 20 tertiary hospitals in China,including Guang'anmen Hospital of the Chinese Academy of Traditional Chinese Medicine,during November 2014—September 2017,and the MDASI-TCM scale assessed patient symptoms at the end of radiotherapy,and descriptive statistics and exploratory factor analysis explored symptom burden and the distribution of TCM symptom clusters.Results At the end of radiotherapy,45.1%of patients reported two or more moderate to severe symptoms,with fatigue being the most prevalent and severe symptom.Fatigue(31.4%),cough(30.9%),expectoration(24.1%),distress(23.2%)and shortness of breath(20.9%)were the top five symptoms from the highest to the lowest in the incidence of moderate to severe symptoms.The enjoyment of life(36.4%)had the highest incidence of interference with moderate to severe symptoms.Exploratory Factor analysis extracted three symptom clusters,namely the excessive heat and damaged yin-Spleen and stomach disorders related symptom cluster,the heart and spleen-deficient related symptom cluster,and the lung qi-unfriendly related symptom cluster,with a cumulative variance contribution of 70.1%.Conclusion Lung cancer patients undergoing thoracic radiotherapy have a certain symptom burden at the end of radiotherapy.The identification of symptom burden and symptom group characteristics is conducive to promoting standardization of TCM syndrome differentiation and laying a preliminary foundation for formulating reasonable and effective TCM intervention measures in the future.