Abstract: The aim of this study was to compare the microcharacteristic and active ingredients dissolution behavior between ultrafine powder and common powder of Phellodendri chinensis, and to provide experimental evidence for the ultrafine powder application and the control of particle size.The laser particle size analyzer, SEM and HPLC were used to evaluate the impact of cell wall breaking rate,morphology and dissolution behavior on microcharacteristic and dissolution of powders of P.Chinensis. The result showed that there were significant differences between ultrafine and common powders in microcharacteristic.The extraction rates and dissolution rates of the active ingredients of ultrafine powders were better than those of common powders.An appropriate degree of ultrafine grinding can promote the dissolution of active ingredients of P.Chinensis and the dissolution was influenced by the dissolution medium.The application of ultrafine grinding technology to P.Chinensis was proved to be feasible.

Key words: Phellodendri chinensis, ultrafine powder;microcharacteristic;dissolution