Objective: This study selected the front page data of medical records from January 2019 to December 2022 in a tertiary public hospital to evaluate the changes in hospitalization expenses of stroke patients before and after the DIP payment reform, aiming to provide an empirical reference for the continuous optimization of the reform of medical insurance payment methods. Method: Using the interrupt time series model, this paper analyzes the change trend of hospitalization expenses of stroke patients before and after the reform of DIP payment. Result: Before the DIP payment reform, the total cost of hospitalization per time continued to increase, and after the reform, there was a reversal of decline. The slope of long-term monthly changes in treatment costs, diagnosis costs and drug costs was significantly lower than that before the reform; The DIP payment reform has effectively reduced the average total hospitalization cost of the two types of medical insurance patients, but the short-term policy impact on employee basic medical insurance patients is significant, and the long-term impact on resident basic medical insurance patients is more obvious; The long-term and short-term cost reduction effects of DIP settlement on the treatment cost and drug cost of surgical patients and the diagnosis cost and drug cost of non-surgical patients were significant. Conclusion: The DIP payment reform has prompted medical institutions to strengthen the cost control of diagnosis and treatment, so that the average total cost of hospitalization of stroke patients has shown a downward trend as a whole, but the impact on the cost of different types of patients is different. It is suggested that medical insurance agencies should strictly formulate the auxiliary catalogue of disease severity, earnestly implement the grouping scheme of DIP payment version 2.0, and improve the accuracy of DIP settlement in combination with clinical pathway management to ensure the quality and efficiency of medical services.