[Objective] To study the optimum extraction technology of flavonoids from H. cordata leaves and the antimicrobial effect of ethanol extracts from H. cordata leaves. [Method] With 70% ethanol as solvent, L9(34) orthogonal test was designed to optimize the extraction technology of flavonoids from H. cordata leaves. Then, the antimicrobial activity of ethanol extracts from H. cordata leaves against B. polymyxa, E.coli, S. aureus, B. subtilis, S. pombe, S. cerevisiae and A. niger was investigated. [Result] The optimum condition for extracting flavonoids with ethanol was based on twice extraction of each 2 h at 80 ℃ with the solid-liquid ratio of 1∶20 g/ml. Under the above condition, the extraction rate of flavonoids from H. cordata leaves was 4.363%. Ethanol extracts of H. cordata leaves had broad-spectrum antibacterial activity, which was more effective for bacteria than fungus. The minimum inhibitory concentration of H. cordata leaves extracts against B. polymyxa, E.coli, S. aureus, B. subtilis, S. pombe, S. cerevisiae and A. niger was 0.06, 0.06, 0.08, 0.08, 0.1, 0.1 and 0.1 g/ml, respectively. [Conclusion] This study could provide theoretical basis for the further development and utilization of H. cordata leaves. [Objective] To study the optimum extraction technology of flavonoids from H. cordata leaves and the antimicrobial effect of ethanol extracts from H. cordata leaves. [Method] With 70% ethanol as solvent, L9 (34) orthogonal test was designed to optimize the Then, the antimicrobial activity of ethanol extracts from H. cordata leaves against B. polymyxa, E. coli, S. aureus, B. subtilis, S. pombe, S. cerevisiae and A. [Result] The optimum condition for extracting flavonoids with ethanol was based on twice extraction of each 2 h at 80 ° C with the solid-liquid ratio of 1:20 g / ml. Under the above condition, the extraction rate of flavonoids from H. cordata leaves was 4.363%. Ethanol extracts of H. cordata leaves had broad-spectrum antibacterial activity, which was more effective for bacteria than fungus. The minimum inhibitory concentration of H. cordata leaves extracts against B. polymyxa, E. coli, S. aureus, B. subtilis, S. pombe, S. cerevisiae and A. niger was 0.06, 0.06, 0.08, 0.08, 0.1, 0.1 and 0.1 g / ml, respectively. [Conclusion] This study could provide theoretical basis for the further development and utilization of H. cordata leaves.