In order to investigate nootropic active chemical constituents of YIZHI compositae decoction, a kind of clinically proved recipe, compounds were isolated from the water extract of YIZHI compositae, bio-assayed with activities on anti-acetylcholinesterase (AchE). 38 compounds were obtained by using column chromatography of silica gel, non-polar macroreticular resin, Sephadex LH-20, ODS and HPLC. 36 of them were identified on the basis of spectral analysis (UV, IR, EI-MS, FAB-MS, 'H-NMR, 13C-NMR, 2D-NMR) and ...