Objective To explore the correlation between the immune related adverse(irAEs)reactions in patients treated with pembrolizumab and traditional Chinese Medicine(TCM)constitution.Methods A total of 110 patients diagnosed with non-small cell lung cancer for the first time were selected.When receiving pembrolizumab immunotherapy for the first time,a general information questionnaire,a TCM constitution classification and judgment scale,an immune related adverse reaction follow-up record book,and a patient's self-perception diary were used to investigate and analyze the TCM syndrome and adverse reactions of the patients.Results Among non-small cell lung cancer patients,there were more than four TCM constitutions,with 48 cases(43.64%)having a calm constitution,20 cases(18.18%)having a biased constitution,30 cases(27.27%)having a yang deficiency constitution,and 12 cases(10.91%)having a yin deficiency constitution.Qi deficiency and Yang deficiency were more prone to fatigue,while Yang deficiency was more prone to rash;Qi deficiency and Yin deficiency were more prone to itching;Yang deficiency was more prone to diarrhea;Non-small cell lung cancer patients with mild constitution were less prone to immune related adverse reactions.Conclusion TCM constitution is related to irAEs,which could predict the occurrence of immune related adverse reactions from the perspective of TCM constitution and intervene in adverse reactions early.