Abstract: The present work aimed to explore the antibacterial effect and potential inhibitory mechanism of three kind of Chinese herbal medicine against Escherichia coli. The experiment used plate count method to test the extract of herbal medicine on the inhibitory effect of Escherichia coli, and utilized doubling dilution method to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). At different time periods, the absorbance values of bacteria liquid and conductivity of Escherichia coli were determined by Ultraviolet spectrophotometer. After 10 hours cultured in a nutrient broth with drugs, through scanning electron microscopy (SEM) to understand the effect of three kinds of Chinese herbal medicine on ultrastructural of Escherichia coli. The result showed that all the herbal medicine displayed a better antibacterial effect against Escherichia coli. The MIC value of Pyrola was 31.25 mg/mL and its MBC value was 62.50 mg/mL; the MIC value of others were both 62.50 mg/mL and the MBC value were 125 mg/mL. It can be discovered that the growth of Escherichia coli in dosing group was restrained and its permeability of cytomembrane was increased. The observations by SEM revealed that Escherichia coli cells got longer and cell surface appeared a lot of pits. It can be concluded that three kinds of Chinese herbal medicine had strong antibacterial effect and Pyrola was more effective against Escherichia coli.