Objective To compare two methods for calculating antimicrobial use density (AUD), select the more suitable AUD for monitoring and management, and achieve rational assessment of AUD. Methods A calculation model for real-time monitoring on AUD and AUD of discharged patients was established. The AUD of 13 clinical departments and the whole hospital of a hospital from January to May 2023 calculated by two calculation methods was statistically analyzed, the dispersion was compared to evaluate their applicability, the impact of two calculation methods on departmental assessment was measured. From June 2023, the real-time monitoring AUD system began to be adopted to achieve triple monitoring on departments, doctors, and drugs. From July, assessment was initiated, changing trend of AUD calculated by two calculation methods after control in 2023 was compared. Results AUD of real-time monitoring had a smaller department monthly dispersion compared with the AUD of discharged patients, with no significant difference among the whole hospital, making the assessment more rational. After implementing management based on real-time monitoring of AUD, defined daily doses (DDDs) decreased by 4.54 in June 2023, and decreased by 2.75 DDDs in the whole year of 2023. Conclusion Real-time monitoring on AUD can better reflect the actual medication level, is more applicable, and is conducive to scientific management of AUD.