Using the interrupt time series model，this paper analyzes the trend change in hospitalization expenses of stroke patients before and after the reform of diagnosis - intervention packet（DIP） payment. The slope of average hospitalization expenses shows a continuous upward trend before the DIP payment reform，but declined after the reform. Similarly，the slopes of treatment fees，diagnostic fees，and drug costs also show a significant decrease compared to the time before the reform. The DIP payment reform has effectively reduced the average total hospitalization cost of the two types of medical insurance patients. The short-term policy effect is significant on employees’medical insurance patients，while the long -term policy effect on residents’medical insurance patients is more distinct. The long-term and short-term effects of DIP payment reform have resulted in significant reductions in the treatment and drug costs for surgical patients，along with the diagnosis and drug costs of non - surgical patients. DIP payment reform can effectively constrain the unreasonable increase of hospitalization expenses for stroke patients，while the impact on the expenses of different types of patients varies. This study suggests continuously deepening the payment reform，setting up a reasonable incentive mechanism，and strengthening the supervision of medical service quality in combination with clinical pathway management.