Isomeric triterpenic acids of oleanolic acid (OA) and ursolic acid (UA)(as Fig.1) both have very low ultraviolet absorption and always exist in the same plant,so the separation and simultaneous determination of them have been a difficult task.In this study,a sensitive method combing dispersive liquid-liquid microextraction (DLLME) with HPLC-UV detection was developed for the preconcentration and determination of OA and UA in traditional Chinese medicinal herbs (CMHs).