Abstract:Objective：To analyze the causes of high and low cost cases under the dip payment reform，and explore control measures for abnormal expense cases in combination with the payment reform process and hospital development needs. Method：The study focuses on the cost abnormal cases discharged from the First People’s Hospital of Huai’an City in the first half of 2024. The hospital DIP payment settlement results are used as the data source. Firstly，chi square test is used to observe the differences between cases with ultra-low costs and cases with normal costs in the Z51 disease group from four dimensions；The second is to use grey relational analysis to observe the cost characteristics and clinical diagnosis and treatment behavior of cases with high hospital costs from the cost structure of the entire hospital. Results：among z51 diseases，there were significant differences in hospitalization days，disease score，case balance rate and drug consumption ratio between the patients with ultra-low cost and those with normal cost（P < 0.05）. In the cost structure of super high cost cases，the grey correlation degree of drug cost is the highest. Conclusion：Strengthen the communication with the medical insurance department to narrow the gap between the medical insurance payment and the actual resource consumption；Internally，we should strengthen the management of cases with abnormal expenses，improve the accuracy of medical records，improve the clinical pathway according to the characteristics of the disease，standardize the diagnosis and treatment behavior，and continuously improve the ability of cost control.