Abstract: The floral colors and the pigments composition in six blooming phases of Paeonia lactiflora Pallas which was introduced from Hexigten，Inner Mongolia were determined. The floral color in different blooming stages was measured by the Royal Horticultural Society Colour Chart（R.H.S.C.C.）and a NF333 spectrophotometer. Its anthocyanins and other flavonoids were subsequently analyzed qualitatively and quantitatively by the high-performance liquid chromatography coupled with diode array detection（HPLC-DAD）and HPLC electrospray ionization mass spectrometry（HPLC-ESI-MS²）. And the relationship between petal colors and anthocyanin contents was explored by multiple linear regression analysis. The results indicated that，during the blooming period，the floral lightness increased while the value of chroma decreased，and the floral color changed from red purple（N57A）to violet（75C）. In all，6 kinds of anthocyanins，4 kinds of flavone glycosides（luteolin 7-O-galloylglucoside，luteolin 7-O- arabinoside）and 15 kinds of flavonol glycosides were detected from petals of Paeonia lactiflora Pallas. Among these compounds，2 kinds of anthocyanins（peonidin-3-O-galloylglucoside-5-O-glucoside，peonidin-3-O-malonylglucoside-5-O-glucoside），2 kinds of flavone glycosides，and 13 kinds of flavonol glycosides were detected for the first time. The analysis showed that peonidin-3,5-di-O-glucoside（Pn3G5G）was the main anthocyanin which took up 93.93% of the total anthocyanins content（TA），while kaempferol-3-O-glucoside was the main flavonol glucoside with 48.78% of the total flavones content（TF）. In addition，during the six blooming stages，TA increased slightly from the Pigmented stage to the Unfold-petal stage of flowering and decreasedOn the contrary，TF decreased during the first two stages，and then increase continuously. At the last，the multiple linear regression analysis show that the contents of Pn3G5G，isorhamnetin-3-O-glucoside，quercetin-3-O-glucoside，quercetin-7-O- glucoside were linear correlation with the floral color changing.edd after that.

Key words: herbaceous peony, anthocyanin, flavonoid, floral color, HPLC-MS