OBJECTIVE To explor e the effect of clinical pharmacists participatin g in fine management of pharmaceutical affairs among the inpatients in the department of gastroenterology based on diagnosis related groups （DRG）data. METHODS The discharged patients in the gastroenterology department of our hospital were selected as the research objects to compare the changes of DRG indicators and hospitalization related indicators before （from April to December 2019）and after （from April to December 2020 and from April to December 2021） pharmacists participating in fine management of pharmaceutical affairs in the gastroenterology department. The key DRG with the highest number of enrolled cases and DRG cases of the total cost overrun were analyzed to explore the deviation of various costs. The rationality of drug use was evaluated for the cases in each DRG that exceeded the benchmark hospital payment standard by three times ，with the help of prescription doctor ’s advice review. RESULTS In the first year of intervention ，the case combination index value of gastroenterology department was increased ，meanwhile，the cost consumption index ，time consumption index and average hospital stay were decreased significantly （P＜0.01）. In the second year of intervention ，total weight of the cases in gastroenterology department was increased ，while cost consumption index ，time consumption index ，hospitalization cost per time ，drug cost per time and average hospital stay were all decreased significantly ， compared with before intervention （P＜0.01）. Among the top five DRG ，the drug cost per time in the GZ 15，GZ13 and GJ 15 were all decreased significantly in the first year of intervention ；hospitalization cost per time and drug cost per time in the GZ 15，GZ13， GJ15 and GJ 13 were all decreased significantly in the second year of intervention （P＜0.01）；after the intervention of clinical pharmacists in DRG over-expenditure cases ，the over-expenditure rate decreased significantly （P＜0.001）. CONCLUSIONS The fine management of pharmaceutical affairs in our hospital has achieved certain results and promotes the rationality of clinical drug use，and provides a new entry point for the cost control and utilization of medical institutions under the background of 〔2020〕68号） DRG.