OBJECTIVE:To investigate the dissolution of Corydalis yanhusuo fine powder and its ultrafine powder in order to provide theory basis for improving the bioavailability of preparation.METHODS:The paddle method was applied to prepare test sample solution and HPLC was used to determine the content of tetrahydropalmatine.The dissolution of C.yanhusuo fine powder and its ultrafine powder were calculated.RESULTS:The dissolution and dissolution rate of C.yanhusuo ultrafine powder were all higher than its fine powder.CONCLUSION:Micronization contributes to the dissolution of effective components.