Abstract: In order to explore the antimicrobial effect of cumin essential oil, common pathogenic bacteria, such as E. coli was treated as the research object to be qualitatively analyzed by agar diffusion, minimum inhibitory concentration (MIC), minimum bactericide concentration (MBC), bacterial growth kinetics and time-kill assay. And then electron micrographs and test of relative conductivity were applied to discuss the mechanism of antibacterial activity of cumin essential oil. The results showed that, the cumin essential oil could most effectively inhibit the growth of E. coli and S. flexneri, whose MICs and MBCs were all 25 and 50 μg/mL, respectively. The possible mechanism was that the cell relative conductivity of bacteria was changed by cumin essential oil, and abnormal changes occurred to the cells, such as shrinkage, local deformation, damage to cell wall and membranes, and loss of cytoplasm. And finally the cells were dead.The above results demonstrated that cumin essential oil could inhibit the growth of bacteria.