Abstract: Due to the advantages of polymer micelles and the anticancer activity of doxorubicin (DOX), the polymer micelle of DOX is expected to be used for drug delivery in anticancer applications. As a biocompatible and biodegradable polymer, amphiphilic copolymer heparosan-adipic dihydrazide-vitamin E succinate (KV) can be self-assembled to form micelles with core-shell structure in aqueous phase. In this article, KV conjugates with two different degrees of substitution (DS) were synthesized to load DOX and were characterized by ¹H NMR. The size distribution, morphology, zeta potential and release behavior in vitro of the DOX-loaded micelles were studied. In vitro cytotoxicity was investigated by MTT assay against MGC80-3 and COS7 cells. The cellular uptake of the DOX-loaded micelles was observed by fluorescence microscopy and flow cytometry. The ¹H NMR spectra results confirmed the KV polymers were successfully conjugated and the degree of VES grafted on heparosan polysaccharide were 12% and 25%. Briefly, the micelles with two different DS were expressed as KV₁₂ and KV₂₅. The DOX-loaded micelles could resist serum adsorption because of the negative charge on the surface. The average particle size measured by dynamic light scattering (DLS) method was 140-150 nm and the TEM results indicated that the morphology of DOX-loaded micelles were spherical. The encapsulation efficiency and drug loading were 80% and 10%-15%, respectively. The DOX-loaded micelles had sustained release behavior and the cumulative release of DOX/KV₁₂ was slightly higher than DOX/KV₂₅. Moreover, the viabilities of cells which were co-incubated with blank micelles were greater than 90%. It is clear that the blank micelles almost non-toxic to both cells. The IC₅₀ of drug-loaded micelles against COS7 cells was much higher than that of MGC80-3 cells and the DOX/KV₁₂ exhibited greater cytotoxicity. The cellular uptake of DOX/KV on MGC80-3 was greater than COS7 cells. In this study, KV polymer micelles have a sustained drug release activity and have a good selectivity to tumor cells, so it would be a potential carrier in drug delivery.