Abstract: Dye intermediate dicyano-4-nitroaniline was determined by thin-layer chromatography and ultraviolet photometry.This method has been used to determine the major composition and impurities in synthetic product with satisfactory result.Compared with classical chermical method,it is simple,rapid and more accurate,The recovery is 99.1%-101.0%.The relative standard deviation is 0.08%-0.85%. Beer's law is obeyed,for sample of 0-6mg/L.