pH-Zone-refining counter-current chromatography was successfully applied to the enrichment and separation of alkaloids from a chloroform extract of Sinomenium acutum.The enrichment was first performed with a classical biphasic liquid system composed of Methyl tert-butyl ether (MtBE)—acetonitrile (CH3CN)—water (4∶1∶5,v/v),10 mM triethylamine (TEA) was added to the upper organic stationary phase as a retainer and 10 mM hydrochloric acid (HCI) to the aqueous mobile phase as an eluter,which could enrich the alkaloids from the crude extract.Followed by a preparative separation,the system was consisted of MtBE—CH3CN—water (4∶0.5∶5,v/v),10 mMTEA in organic stationary phase and 5 mMHC1 in aqueous mobile phase,which optimized the separation and purification of the crude extract well.A 1.60 g chloroform extract was enriched in the first separation step,yielding 0.82 g crude alkaloids.