Objective:To explore the participation of clinical pharmacists in drug treatment. Methods:Clinical pharmacists car-ried out pharmaceutical ward round, and understood the medication history of one breast cancer patient with postoperative pneumonia. They thought the induction possibility of trastuzumab likely to be non infectious pulmonary infiltration. Combined with the drug instruc-tions, relevant literatures and case report, they put forward suggestions for the medication, and participated in the formulation of drug therapy. Results:The suggestions of clinical pharmacists were adopted, and on the second day of methylprednisolone sodium succinate treatment, the symptoms of the patient were improved, and the results of the imaging examination also tended to be improved without recurrence. Conclusion:The participation of clinical pharmacists in the formulation of clinical medication has important significance for improving the level of clinical treatment.