Drug delivery system has great significance for the targeted treatment of cancer. A cyclized & branched amphiphilic block copolymer was synthesized by DE-ATRP with brominated polyethylene glycol (PEG2KBr) as initiator and di(2-acry-loyloxy ethoxy)-[4-methoxy-phenyl]methane (ACD) as hydrophobic monomer and explore for its potential application to drug delivery. The structure of polymer was characterized by hydrogen spectrum nuclear magnetic resonance (1HNMR) and gel permeation chromatography (GPC). The size and morphology of micelles was measured by dynamic light scattering (DLS) and transmission scanning microscopy (TEM). The structure was identified to be branched-cyclized. The blank micelles were spherical with the size of 70 nm, and Doxorubicin hydrochloride loaded micelles were with the size of 90 nm. The drug loading efficiency was 48.7%, DOX-loaded micelles have good pH-responsive and drug release. It is proved that the polymer has a certain application value in drug delivery system.