OBJECTIVE：To explore the role of clinical pharmacists in the diagnosis and tre atment of immune checkpoint inhibitor related adrenocortical insufficiency ，so as to provide reference for the diagnosis and treatment of similar cases. METHODS：A lung squamous carcinoma patient with tumor immunotherapy ，who received long-term intravenous infusion of Pembrolizumab injection ，was hospitalized for more than 10 days due to fatigue and poor appetite. The clinical pharmacists consulted the literature and evaluated the correlation of ADR on the basis of patient ’s physical examination results （plasma cortisol 16.41 nmol/L at 8：00 in the morning on the second day of admission ，adrenocorticotropic hormone 8.39 pg/mL，serum electrolyte sodium 126.00 mmol/L，chlorine 88.00 mmol/L，etc.）and medication history （receiving the treatment with immune checkpoint inhibitors）. The clinical pharmacists assisted the doctor to confirm that the patient was adrenocortical insufficiency ，and the correlation with pembrolizumab was “very likely ”. On the basis of discontinuation of pembrolizumab ，it was recommended to take Hydrocortisone tablets orally （20 mg at 8：00 in the morning and 10 mg at 4：00 in the afternoon ）for glucocorticoid physiological dose substitution therapy. Before treatment ，the patient and his families should be educated on the use of drugs ，pharmaceutical care should be implemented to evaluate the glucocorticoid doseand efficacy during treatment ，and medication education was carried out at discharge. RESULTS ：The doctor adopted theli_xyan suggestions of the clinical pharmacist. On the 5th day after @126.com administration，the symptoms of adrenocortical insufficiency were significantly impro ved，and the patient was discharged with medicine. CONCLUSIONS ：During the treatment of the patient ， the clinical pharmacist gave full play to his pharmaceutical expertise ，assisted the doctor to formulate an appropriate medication plan，and carried out medication education for the patient and his family members ，so as to ensure the effectiveness and safety of the patient ’s medication. It is suggested that the baseline examination of patients should be improved before immune checkpoint inhibitor treatment ，including physical examination and plasma cortisol level at 8：00 in the morning ；the frequency of monitoring plasma cortisol level and serum electrolyte level at 8：00 in the morning. should be increased during medication ；the patients should be followed up for at least 1 year after withdrawal ，so as to early detect and treat immune checkpoint inhibitor related adrenocortical dysfunction.