Abstract: A novel series of amphiphilic polymers,MPEG-PLA-β-CD,with different relative molecular weight were synthesized by conjugating MPEG-PLA onto 6-deoxy-6-ethylenediamino-β-cyclodextrin through succinic anhydrideas spacers.The chemical structures were characterized by FT-IR and ¹H NMR.The critical micelle concentrations(CMCs) were determined by pyrene fluorescence probe spectrometry.These polymers could self-assemble into micelles loading hydrophobic drugs.Diameters,the drug-encapsulation efficiency and drug-loading efficiency of the micelles loading ibuprofen were also measured to investigate the properties of polymers as drug delivery systems.According to the results,MPEG 2K-PLA 6.6K-β-CD was a potential drug delivery agent owing to its lower CMC value and higher drug-loading efficiency.