To establish the reference standard of bisacodyl for assay, the refined bisacodyl was obtained by purify bisacodyl bulk drug, and was identified by UV, IR, and DSC; its purity and absolute content were determined by the method of TLC, HPLC, DSC, and potentiometric titrationThe related substances of refined bisacodyl were below 1% determined by TLC; the absolute contents of refined bisacodyl obtained by the method of HPLC, DSC, and potentiometric titration were 99.6%, 99.5%, and 100.6%, resp.The purity of refined bisacodyl complied with the requirement of reference standard for assay.