AIM:To prepare a compound as the chemical reference substance of Guangjinqiancao Zonghuangtong Capsule.METHODS:To apply general column chromatography combined with preparative HPLC to isolate the target compound,to use analytic HPLC to determine the purity,stability and its content in the capsule,and to employ spectroscopic analysis (UV,IR,ESI-MS,1H-NMR,13C-NMR,DEPT,1H-13CCOSY,1H-1HCOSY,1DHOHAHA.1D.NOE,HMBC) to elucidate the structure of the isolated compound.RESULTS:The obtained compound was identified as isoschaftoside with the purity of over 99%, which was stable within 3 months at ambient temperature.As for isosehaftoside solution.it was stable within 8 h at ambient temperature.Its content in the capsule was above 3.0%.CONCLUSION:Isoschaftoside is a qualified reference substance for analytic assay ofGuangjinqiancao Zonghuangtong Capsule,and can be isolated from Desmodium styracifolium(Osb.)Merr.