Abstract: The methoxy poly(ethylene glycol)-poly(lactic acid)(mPEG-PLA) copolymer was synthesized by ring opening polymerization using methoxy poly(ethylene glycol)(mPEG) and D, L-lactide(D, L-LA).The dihydroartemisinin (DHA)-loaded copolymer micelles(DHA/mPEG-PLA) were prepared via solvent evaporation method.The chemical structure and property of copolymer were characterized by Infrared Spectroscopy(IR), proton Nuclear Magnetic Resonance(¹H-NMR) and contact angle measuring instrument.The size and morphology of the micelles were investigated by Nano ZS90 Zetasizer and Scanning Electron Microscopy(SEM).Results showed that the critical micelle concentration(CMC) of copolymer was 7.71 mg/L.The DHA/mPEG-PLA copolymer micelles were spherical in shape with average particle sizes of (118.1±1.9) nm, the entrapment efficiency and the loading capacity were (77.1±0.3)% and (2.7±0.1)%, respectively.The apprarent solubility of DHA in micellar solution was increased about 1.5 times as compared with DHA in aqueous solution.After 39 h of UV irradiation, the degradation rate of DHA in suspension was 37% and it still showed a rising trend, while the degradation rate in micelles tended to be a constant(10%).