Antibiotics are certainly beneficial to treat the bacterial infection. However, inappropriate use puts patients at danger for avoidable adverse drug reactions. This inappropriate use accelerates the emergence of resistance and potentially increases overall health-care costs. In oriental pharmacology, herbal medicines had been used as an antibiotic drug, but its antibiotic mechanism has not yet been proved completely. Here, we studied the antibiotic effects of $Agrimonia$ $pilosa$ on $E.$ $coli$ O157:H7. Especially, it is noteworthy that the antibiotic efficacy of the herb extract on three proven targets for a main antibiotic drug: bacterial cell wall biosynthesis, protein synthesis and DNA replication and repair. The results show the antibiotic effects through the inhibition of bacterial cell wall synthesis, folic acid synthesis, and multidrug efflux.