Three kinds of novel unsaturated quaternary ammonium were synthesized with the starting material of 5-chloromethylsalicylaldehyde and unsaturated tertiary amines including dimethylaminoethyl methacrylate(DMAEA), N,N-dimethyl allyl amine(DMAA) and N-methyl-diallylamine(DAMA), and optimized conditions of the model reaction. Through optimizing the reaction conditions, we concluded the ideal conditions：dichloromethane as a solvent, the reaction molar ratio of 5-chloromethylsalicylaldehyde and unsaturated tertiary amines is n(1):n(2a)= 1:1, the reaction temperature is 0℃, and the reaction time is 10 h. Under optimal conditions, the yield of the compounds is all above 90%. The obtained products have been characterized by melting point, IR, 1HNMR, 13CNMR and ESI-MS spectra. Antibacterial activity of the compounds using Oxford Cup were tested. The results showed that three kinds of quaternary ammonium (3a, 3b, 3c) all have good antibacterial activity against Staphylococcus aureus, while there is no significant antibacterial activity against E. coli.