Objective: To optimize polymer materials and preparation process of puerarin sustained-release microspheres. Method: The microspheres were prepared by emulsion solvent evaporation method.Taking composite score of encapsulation efficiency

drug loading and yield as index

polymer materials and formulation process were optimized by orthogonal design.The microspheres were characterized by different techniques

such as scanning electron microscopy (SEM)

thermogravimetric analysis (TGA)

differential scanning calorimetry (DSC)

X-ray diffraction (XRD). Result: Optimum polymer material of puerarin sustained-release microspheres was polylactic acid (PLA)

optimum preparation parameters were as follows:dosage of 37.5 mg

PLA of 80 mg

polyvinyl alcohol (PVA) of 0.5%.Surface of puerarin sustained-release microspheres was smooth and round without adhesions

average particle size was 104.3 μm

drug loading was (26.20±2.24)%

encapsulation efficiency was (68.92±1.88)%

yield was (83.97±2.55)%.TGA

DSC and XRD were indicated changes in physical form of molecular spatial relationship of copolymer and puerarin in the microspheres. Conclusion: Puerarin sustained-release microspheres can be successfully prepared by emulsion solvent evaporation method

optimized process is simple and reasonable.