Abstract: On the basis that amino acid reacts with acetyl acetone and formaldehyde to form fluorescence compounds,a synchronous fluorospectrophotometric method for determining the concentration of total amino acid in chrysanthemum of Chuzhou was established. Phenylalanine was used as a standard and the optimized conditions found were as follows:① wavelength difference of phenylalanine and glutamate is 55 nm;② wavelength difference of glycine and the mixture of glycine,glutamate and phenylalanine is 60 nm;③ pH of reaction system is 6.0;④ temperature of reaction is at 100 ℃;⑤ reaction time is 60 min;⑥ amount of 4% formaldehyde solution is 1.5 mL;⑦ amount of 2% acetylacetone solution is 1.25 mL. Linear relationship between values of fluorescence intensity and mass concentration of phenylalanine was kept in the range of 5.00-50.0 mg·L-1,with detection limits (3s/k) in the range of 0.30-0.87 mg·L-1. The method was carried out 10 times with phenylalanineand value of RSD found was 1.2%. Test for recovery was performed by standard addition method,giving recovery in the range of 64.7%-103%.