Objective To improve the quality of antibacterial drugs preparation in Pharmacy Intravenous Admixture Service （PIVAS）. Methods Lean management was applied in antibacterial drugs preparation in PIVAS, with measures including: making better spatial layout of PIVAS, optimizing prescription checking system, ratcheting up visualization in management, refining the medicine preparation process, modifying transportation process, and mending quality control process.Before（May to July 2019） and after （August to October 2020） lean management practice, the relevant process outcome indicators were compared. Results The daily prescription checking time,dispensing time,preparing time,packing time and delivery time for antibacterial drugs were significantly lower than those before lean management practice（P＜0.01 for all）; the rates of non-qualified prescriptions and errors, and the number of particles in prepared drug saw a significant drop from before （P＜0.01 for all）.The satisfaction rate of nursing staff was significantly higher than before lean management （P＜0.01）. Conclusion Implementation of lean management in PIVAS can optimize the preparation and dispensing processes of antibacterial drugs, reduce the incidence rate of errors in drug preparation, improve the timeliness of drug preparation,and ensure medication safety in clinical settings.