Aim: This study aims (1) to isolate different types of compounds from Alismatis Rhizoma, a well-known traditional Chinese medicine, (2) to compare the anti-cancer activities in vitro, and (3) to study the structure-function relationship.Methods: Silica gel column chromatography and preparative HPLC were used to isolate the compounds and spectroscopic techniques including UV, MS, 1H-NMR, and 13C-NMR were employed to elucidate the structures.