BACKGROUND Owing to its broad-spectrum antibacterial activity, strong antibacterial effects, and ß-lactamase stability, cefoperazone/sulbactam has been recognized as a first-line empirical drug for treating severe infections. However, its administration is also characterized by numerous adverse effects, including coagulation dysfunction. Here, we summarize past clinical treatment data to provide data support for clinical use of cefoperazone sulbactam. MATERIAL AND METHODS We retrospectively analyzed the clinical medical records of 820 patients treated with cefoperazone/sulbactam from January 2015 to December 2020. A retrospective cohort study design was used. We assessed the general data of patients, age and sex distribution, type of primary disease, and incidence and days of abnormal blood coagulation with cefoperazone sulbactam. The chi-square test and t test were used to analyze the effect of cefoperazone sulbactam on coagulation function and the effect of vitamin K intervention on prognosis. RESULTS The rate of coagulation dysfunction was 24.39% (200 patients). Among these 200 patients, 50 were treated with vitamin K1. With increasing patient age, the number of patients with cefoperazone/sulbactam-induced coagulation dysfunction increased (peak at 81-90 years). APACHE II of coagulation dysfunction (15.54±4.095) was significantly higher than that in the normal group. It occurred at days 2-19 after administration of 9.0 g/day of cefoperazone/sulbactam. Measured coagulation indices were significantly higher after treatment with cefoperazone/sulbactam than before treatment, including international normalized ratio, prothrombin time, and activated partial thrombin time (P<0.0001). CONCLUSIONS All coagulation indices decreased significantly after vitamin K1 intervention, indicating improved coagulation function, especially in patients with high APACHE II scores. Hence, regulated vitamin K1 administration can benefit patients with coagulation dysfunction in clinical treatment.