Carmustine (BCNU)-loaded polylactic acid microspheres were prepared by spray dry method, and effects of technol. process on morphol. and drug release behavior were studied. BCNU and polylactic acid were co-dissolved in acetone, chloroform or Et acetate, and then submitted to spray drying. The morphologies of microsphere obtained under different process conditions, such as polymer concentration and inlet temperature of spray drier, were observed by TEM. The stability of BCNU after the spray drying was studied using 1H-NMR anal., and the drug release behavior was investigated through spectrophotometer. BCNU-loaded polylactic acid microspheres were prepared using chloroform or Et acetate as solvent, while the particles with irregular shape were obtained with acetone as solvent, resulting in the fast release rate of the BCNU from these microspheres. The drug-loading was ranged from 14%-42%. BCNU-loaded polylactic acid microspheres can be prepared using spray drying technique with Et acetate as solvent.