To study the chemical constituents from flowers of Koelreuteria paniculata.Column chromatography and spectral analysis were used to isolate and identify the constituents.The EtOAc fraction from flowers of Koelreuteria paniculata was separated and purified. Nine compounds were obtained and identified as:sitosterol glucoside (I), gallic acid (II), kaempferol (III), luteolin (IV), kaempferol-3-O-(6"-acetyl)-beta-D-glucopyranoside (V), hyperoside-2"-O-acetyl (VI), hyperoside-2"-O-galloyl (VII), hyperoside (VIII), kaempferol-3-O-D-glucopyranoside (IX).Nine compounds are isolated for the first time from flowers of Koelreuteria paniculata. Compounds IV, V, VI and IX are isolated from this genus for the first time.