In this paper,the quaternary ammonium salt(QAS-1) was prepared with N-methy imidazole and N-methyl diethanol amine.It was characterized by FT-IR,NMR and TOF-MS.Its antibacterial properties against S-aureus,α-H-tococcus,E-coli and P-aeruginosa were subsequently evaluated by paper disk method and shake culture method,which showed that it has a good antibacterial effect.Especially,the antibacterial effect against gram-negative bacteria(E-coli and P-aeruginosa) is more obvious and better than positive control(chlorhexidine).