A cationic surfactant dodecylguanidine hydrochloride was synthesized and the optimized reaction conditions were: n(dodecylamine)∶n(cyanamide)∶n(hydrochloride)=1∶1.5∶1.1, refluxed for 2h in ethyl alcohol solvent. The structure of product was confirmed by IR, 1H-NMR and elemental analysis. The properties of the product were measured, such as surface activity, foaming and emulsifying power, and antimicrobial capacity. Results showed that cmc of the product is 5.5mmol/L, γcac is 24.1mN/m. The product had better foaming and lower emulsifying abilities than DTAC. The inhibitions of cell viability for Staphylococcus aureus and Escherichia coli are 100% at the concentration of 25mg/L and for Candida albicans is 99.5% at the concentration of 100mg/L respectively.