Abstract: In this paper，we explored the flower color variation，pigments distribution and content during the flowering period in tree peony cultivars named‘Jinyi Hualian’and‘Xiaguang’respectively using Colour Chart of the Royal Horticultural Society（RHSCC）and colorimeter，tissue sections，and high performance liquid chromatography with a photodiode array detector. Four kinds of anthocyanins and 14 kinds of flavonoids were detected from two tree peony cultivars. They are mainly distributed in epidermal cells，whereas no or only a few flavonoids were found in palisade tissue. Our results suggested that the flower lightness（L*）of the two cultivars increase，whereas the chroma（C*）and redness decrease during flowering period with the flower color changing from red yellow bi-color and red to light yellow and orange yellow respectively. The pigments composition of two cultivars remained unchanged during this period；but there was a significant change in pigment content. Total anthocyanins（TA）and total flavonols （TF）decreased sharply；And the content of TA decreased sharper compared with TF. Overall，the results indicated that the difference in anthocyanins and flavonoids degradation rates during the flowering periodhad caused the color to change from red to orange and yellow，and could be the main contributing factor for changes in flower color.

Key words: tree peony, flower color, anthocyanins, flavonoids, high performance liquid chromatography