[(2 – alkyl-1, 3 - dioxane -4) methyl] - 1 – benzimidazole was prepared through condensation reaction using aldehyde, epoxy bromopropane and benzimidazole as raw materials. The resulting reacted with dimethyl sulfate to afford two acetal cationic surfactants containing benzimidazole of 1 - [(2 - hexyl 1, 3 - dioxane -4) methyl] - 1 - methyl - methyl sulfate benzimidazole (3a) and 1 - [(2 - nonyl 1, 3 - dioxane -4) methyl] - 1 - methyl - methyl sulfate benzimidazole (3b). The optimal synthetic condition of intermediate [(2 – nonyl- 1, 3 - dioxane -4) methyl] - 1 - benzimidazole was: n (capric acetal): n (benzimidazole): n (NaOH) = 1:1.1:4, refluxing for 24h. The yield of intermediate was 52.0%. The surface properties of 3a and 3b were respective measured. The critical micelle concentration were 1.4 × 10-3 mol / L and 1.2 × 10-3 mol / L in 20℃; Krafft points were lower than 20 ℃; Foam stability was 70.2% and 77.4%; emulsification was the 31min and 33min. The structure of intermediate and target compounds were characterized by IR, 1HNMR spectra.