Objective: The paper attempts to explore the drug auxiliary catalog setting and refined adjustment methods of daytime chemotherapy payment, as well as the setting and adjustment methods of institution level coefficient under the DIP payment, to improve the scientific score formation mechanism and dynamic adjustment mechanism. Method: All hospitalized patients from tertiary hospitals in Xiamen City, Fujian Province from 2021 to 2023 were selected as samples. Univariate and multivariate analyses were conducted on the influencing factors of the medical insurance fund payment amount for hospitalization medical expenses of antitumor drug treatment. The effects of hospitalization days and antitumor drugs on the medical insurance fund payment amount for hospitalization medical expenses, the CV of hospitalization medical expenses and the differences in fees among medical institutions. Results: Antitumor drugs and hospitalization days have a significant impact on the medical insurance fund payment amount for hospitalization medical expenses. Conclusion: Under the DIP payment, it is recommended to set an auxiliary catalog of tumor drugs for some tumor diseases, calculate the scores for daytime chemotherapy and differentiate them effectively from non-daytime chemotherapy for more scientific and accurate payment, adjust the institutional level coefficient for different medical institutions and improve the refined management of medical insurance.