Abstract: N,N-dioctyl，-didecyl，-didodecyl chitosans with different backbone molecular weight were synthesized. A comparative study on the drug release behavior of corresponding self-assembled vesicles was carried out. Morphology studies showed that the curve of N,N-dialkyl chitosan was depended on the length of side chain，and the backbone molecular weight influenced the size of corresponding vesicle. Experimental results of drug release indicated that the drug-releasing rates of vesicles made from longer alkyl chain and/or larger backbone molecular weight of chitosan were slower than the others，and drug-releasing equilibrium amount was smaller as well. Moreover，both drug loading content and encapsulation efficiency of vesicles slightly increased with the length of alkyl chain and/or the backbone molecular weight.