ObJective: To establish a method of evaluating reaction abilities of flavonolds with Fe(Ⅱ) with 9 flavonoids have been investigated in ethanol solution at 20 ℃ by UV-Visible spectroscopy. Result: Based on the changes of the UV-Vis spectra

we could determine that 7 flavonoids (quercetin

myricetin

rutin

kaempferol

baicalin. baicalein and luteolin) occurred complesx reaction

due to the bathochromic shift of the wavelength band. On the other hand. no bathochromic shift as indication for complexation of catechin and chrysin could be observed under the conditions we had chosen. The kinetics of complex formation were investigated with the ligand in zero-order by the presence of Fe(Ⅱ). The reation rate constants in turn were as follows:myricetin>quercetin>baicalein>kaempferol>baicalin>rutin>luteolin. Conclusion: The strongest chelating power is the pyrogallol hydroxyl in ring B

and the pyrocatechol hydroxyl ranks second

a single phenolic hydroxyl relatively weak. When flavonoid aglycones transform into glycosides. their complex capacity will decrease significantly. The system investigated can be considered as a simplified method to evaluate the complex ability between flavonoids and Fe(Ⅱ).