Abstract: Antibacterial effects of volatile oils from 17 kinds of natural plants on Escherichia coli,Staphylococcus aureus,Salmonellas spp. and Listeria monocytogenes were investigated in this study.Inhibition zone and Matlab were employed to determine that the spearmint oil was the optimal solution for inhibiting the bacteria,the MIC and MBC were 6.25 mg·m L^-1and 50 mg·m L^-1respectively. Furthermore,the active ingredients of spearmint oil were identified as limonene( 13.71%) and L(-)- carvone( 71.34%) by using GC- MS,which had better antibacterial activity against E.coli and S.aureus,both MIC and MBC were 12.5 μg·m L^-1.The comprehensive analysis indicated that L(-)- carvone was the main factor for bacterial inactivation.And the SEM results showed bacterial cells were crumpled and ruptured after L(-)- carvone treatment,which demonstrated this substance could effectively suppress bacterial growth and reproduction.