A serial of cation gemini surfactants with dibenzyl ether spacer (10-B-10，12-B-12，14-B-14) were synthesized from 1-bromoalkane, N,N-dimethylethanolamine and α,α'-dibromo-p-xylene. Their structures were identified by FT-IR, 1HNMR and ESI-MS. Aggregation number of micelle of these surfactants was determined by steady-state fluorescence method. The results showed that the CMC determined by steady-state fluorescence method was in agreement with that determined by surface tension method. The critical micelIe concentration (CMC) decreased from 3.24 to 0.056 mmol.L-1 with the alkyl chain length increasing from 10 to 14. The critical aggregation number was 6.98(10-B-10)，3.87(12-B-12) and 1.62(14-B-14). The salt-induced vesicle to micelle transition was found in the aqueous solution of these surfactants by dynamic light scattering(DLS).