OBJECTIVE:To investigate into the effect of the combined use of large-aperture resin adsorption and ultrafiltration on salviol and loganin in Liuwei dihuang Bolus.METHOD:HPLC method was used.RESULT:The weight of the refined extract is only 4.6% that of the original medicinal meterial and meanwhile 98% of salviol and 86% of loganin were retained.CONCLUSION:This combined use technique can effectively reduce the administration dosage and retain the micromolecule effective constitutents.