Abstract: Two novel castor oil-based quaternary ammonium were synthesized from the starting material of methyl ricinoleate by aminolysis reaction and quaternization reaction. Their structures were characterized by means of FTIR, 1H NMR, 13C NMR and ESI (MS) . Bactericidal activity of novel castor oil-based quaternary ammonium salts were evaluated by inhibitory zone diameters against E. coli and S. aureus. It was found that castor oil-based quaternary ammonium salts have antibacterial activity. Antibacterial activity of the N, N-dimethyl-N-ethyl-castor oil acid amide propyl bromide than N-benzyl-N, N-dimethyl-castor oil acid amide propyl bromide.