DL-Lactide and glycolide was synthesized from DL-lactic acid and glycolic acid with Sb₂O₃. We investigated the physicochemical properties of poly(DL-lactide-co-glycolide)(PLGA) synthesized in the ratio of 70 : 30, 80 : 20, and 90 : 10 from these dimers, respectively. Micelles containing clonazepam in PLGA core were prepared easily and in uniform bulk by dialysis methods. We investigated its applications in the drug delivery system(DDS). PLGA properties could be obtained variably in viscosity, average molecular weight, and melting point by copolymerization methods under different conditions of catalysis, temperature, reaction time, and solvents. Micelles of PLGA were made easily and in uniform bulk by dialysis methods and its loaded drug percentages showed 25.4, 23.4, and 22.3%, respectively. Then the critical micelle concentrations(CMC) values of PLGA were 0.049(5.15×10^-7), 0.046(4.10×10^-7), and 0.033 mg/ml(2.40×10^-7 mole). In vitro drug release experiment showed the release time of drug delayed in the order of PLGA(70 : 30) > PLGA(80 : 20) > PLGA(90 : 10). In short, biodegradable PLGA was prospected its applications probability in the micelles of delayed-action drug release and nanoparticle units.