A convenient pathway to control drug release from hybrid assembly nanoparticles of several kinds of copolymers was investigated in this paper. Three kinds of biodegradable amphiphilic copolymers, poly(ethylene glycol)-block-poly(L-lactic acid), poly(ethylene glycol)-block-poly(D,L-lactic acid) and poly(ethylene glycol)-block-polycaprolactone-poly(ethylene glycol) were used to assemble into hybrid assembly nanoparticles as carriers of paclitaxel. The results show that small spherical hybrid assembly nanoparticles (diameter < 100 nm) with good paclitaxel loading ability and entrapping efficiency were obtained simply through hybrid assembling of different copolymers. The in vitro release studies indicate that paclitaxel release rate can be controlled easily by varying the ratio of the hybrid copolymers. The release control mechanism is assigned to the crystallization adjustment of the cores of hybrid assembly nanoparticles which provide a convenient approach to control drug release for drug-loaded nanoparticles.