Abstract: AimTo study the chemical constituents from water extract of Radix isatidis. (Isatis indigotica Fort.). MethodsThe water extract was underwent absorption by D101 macroporous resin, the portion eluted by ethanol of different concentrations was isolated and purified on silica gel column repeatedly. The obtained compounds were identified and structurally elucidated by their physico-chemical properties and spectral analysis. ResultsFive compounds were isolated from water extract of Radix isatidis, and were partly identified separately: 3-［2′-(5′-hydroxymethyl)furyl］-1(2H)-isoquinolinone-7-O-β-D-glucoside (I), lariciresinol-4,4′-di-O-β-D-glucopyranoside (II), lariciresinol-4-O-β-D-glucopyranoside (III), 2-hydroxy-1,4-benzenedicarboxylic acid (IV), mannitol (V). Conclusion Compound I is a new compound and compounds IV and V were isolated from the plant for the first time.