Abstract: A fluorescent method for the synchronous determination of 1-naphylamine and 2-naphylamine was developed.In order to avoid the interference from the two isomers,the synchronous fluorescence and first-order-derivative synchronous fluorescence spectra of the two isomers of naphylamine were studied,and the zero-crossing method for reading spectral intensities was adopted.At pH=7.8(phosphate buffered water solution) and △λ=120 nm,the synchronous fluorescence peaks were at 323 nm and 290 nm for 1-napylamine and 2-naphylamine,respectively.The first order derivative synchronous fluorescence intensities varied linearly with 1-naphylamine and 2-naphylamine concentrations in a range of 4.0×10^-7~2.0×10^-5 mol/L.The relative standard deviations(RSDs) of them were all below 5%.The limits of detection were 4.0×10^-8 and 2.9×10^-8 mol/L for 1-naphylamine and 2-naphylamine,respectively.The method was applied to the simultaneous determination of the two naphylamine isomers with satisfactory results.