Objective： To study the preparation technique for magnetic poly D,L-lactide-co-glycolide phenylarsine oxide nanoparticles （M-PLGA-PAO-NPs） and to characterize the resultant product. Methods： M-PLGA-PAO-NPs were prepared by using emulsion-evaporation process. The morphology of the prepared nanoparticles were observed by transmission electron microscope and the magnetism of the particles was determined by vibrating sample magnetometer. Meanwhile, we also evaluated the mean diameter, encapsulation ratio, and drug loading rate of the particles. Results： The nanoparticles had a regular spherical surface, with 80% of them having a diameter of 140-500 nm. We also found that the drug loading rate of the particles was 3.2% and the mean encapsulation ratio was 34. 2%. The drug had satisfactory magnetic property. Conclusion： Our method can obtain M-PLGA-PAO-NP with satisfactory quality, it is simple-to-use and the prepared particles can meet the requirement of pharmaceutics.[著者文摘]