A special monomer 4-vinylbenzyl N,N-diethyldithiocarbamate (VBDC) was synthesized firstly, and then the cationic copolymerization of VBDC with isobutene was investigated. The results of H-1-NMR, EA and GPC (with UV detector) indicated that VBDC could copolymerize with isobutene and form the copolymer, and the units of VBDC incorporated into copolymer chains increased with the increasing of the feed ratio of VBDC. However, there has apparent discrepancy between the VBDC in the monomer feed and the VBDC incorporated into the copolymer chain, which is probably due to the relatively lower reactivity of VBDC. In the presence of VBDC, the MWD is narrower than that of in absence of VBDC under the similar experimental conditions. For cumyl methyl ether/TiCl4 initiating system, the M-w/M-n could be slightly narrowed from 1.55 (no VBDC) to 1.33 (with VBDC) in the mixed solvents of n-hexane and CH3Cl (15/10,V/V), while cumyl chloride /TiCl4 initiating system, the M-w/M-n is narrowed from about 5.0 (no VBDC) to about 1.5 (with VBDC) with n-hexane and CH2Cl2 (10/10,V/V) as the mixed solvents. When benzyl N, N-diethyldithiocarbamate (BDC) was used as the model compounds instead of the VBDC, the similar results Of M-w/M-n were obtained. These results demonstrated that the VBDC functions as the monomer electron donor (ED) in this polymerization system.