Objective: The paper analyzes the characteristics and influencing factors of the cost ratio of blood transfusion cases, in order to promote the reform and refined management of medical insurance payment methods. Methods: A total of 14864 blood transfusion cases in Luzhou City in 2023 were taken as the research objects, and the cost ratio and influencing factors were analyzed by four-quadrant bubble chart and structural equation model. Results: The overall cost ratio of blood transfusion cases was 1.36, the DIP payment rate was 86.40%. The four-quadrant bubble chart showed that most of the top 20 diseases were located in the first quadrant (high proportion of blood transfusion cases and high cost ratio) and second quadrant (low proportion of blood transfusion cases and high cost ratio). The structural equation model showed that the total effect of the influencing factors of the cost ratio of blood transfusion cases was the length of stay (0.623), CMI value (-0.448), blood fee (0.228), discharge mode (0.060), and treatment mode (-0.034). Conclusion: The cost ratio of blood transfusion cases is relatively high, and the risk of overspending under the DIP payment is relatively high. Blood fee and other factors jointly affect the cost ratio of blood transfusion cases. It is recommended that blood transfusion should be included in the minor surgical operation according to resource consumption and used as the basis for disease grouping. In terms of the diseases with a relatively stable cost ratio and a certain proportion of blood transfusion cases, a blood transfusion auxiliary catalogue with blood transfusion indications as the main basis for correction should be constructed to optimize the medical insurance settlement rules for blood transfusion cases.