Abstract: In a B-R buffer medium of pH 9.15,a ternary complex was formed among Al(Ⅲ),quercetin and borate ion (BO3-3),and its fluorescence property was measured at the wavelengths of (λex) 452 nm and (λem) 516 nm.Linear relationship between values of fluorescence intensity and concentration of quercetin was kept in the range from 1.0×10-7-6.0×10-6mol·L-1.Detection limit (3S/N) of the reaction found was 2.1×10-7mol·L-1.Samples of flossophorae extract were analyzed by the proposed method,and test for recovery was made on these samples as matrixes,giving values of recovery in the range of 101.5%-112.5%.