Abstract: Polylactic acid(PLA) microspheres were prepared by conventional solvent evaporation method using polyvinyl alcohol(PVA)/arabic gum（AG） as the modifier. In order to gain the best parameters for preparing microspheres with homogeneous size, the influences of different factors on average diameter of microspheres were evaluated by orthogonal-designing method. Five factors with four levels were considered in the experiment, which were different modifier, organic solution, PLA concentration, surfactant and agitating rates. The micromeritics characteristics of PLA microspheres were also evaluated. The result shows that the microspheres we prepared have relatively uniform diameter, the optimum even diameters is about 2.0～3.0 μm, and the surface of the microspheres is smooth.

Key words: polylactic acid(PLA), microsphere, orthogonal-designing method, solvent evaporation method