A series of well-defined amphiphilic linear-dendritic block copolymers （telodendrimers, MPEG-b-PAMAM-cholesterol） with 1,2,4 or 8 cholesteryl groups （named as P1, P2, P4, P8, respectively） were synthesized. Their chemical structures were char- acterized with IH NMR and mass spectrum （MALDI-TOF MS）. The telodendrimers could self-assemble into micelles in aqueous solution, and encapsulate chemotherapeutic drug doxorubicin （DOX） and paclitaxel （PTX） for combination therapy. All the telodendrimers could encapsulate DOX with similar capability. However, their drug-loading capability of PTX is in- creased with the increasing number of cholesteryl groups. P8 exhibited much higher PTX loading efficiency than its counter- parts. Thus, P8 was selected for further application of drug delivery in the paper. The drug-loading micellar nanoparticles （NPs） of P8 were spherical in shape and their diameters were less than 150 nm which were determined by dynamic light scattering measurements （DLS） and transmission electron microscope （TEM）. In vitro drug release experiment demonstrated that P8 ex- hibited a controlled release manner for both DOX and PTX, and the two drugs were released simultaneously. In vitro cytotoxi- city experiment further demonstrated that the co-delivery of DOX and PTX in P8 exhibited better anti-cancer efficiency than the delivery systems encapsulated with single drug （DOX or PTX）. This indicates a synergistic effect. The co-delivery system showed potential in future anti-cancer treatment.
