Abstract: A new chromogenic reagent,1-(4′-nitrophenyl)-3-(3″-methylpyridyl)-triazene was synthesized and its structure was characterized by elementary analysis and IR-spectrometry.Its color reaction with zinc(Ⅱ) ion was also studied.In a borate buffer of pH 11.0 and in the presence of Triton X-100,a yellow colored coordination complex was formed between the new color reagent and Zn(Ⅱ) ion with a mole ratio (R∶Zn) of 4 to 1,and its positive absorption maxima and negative maxima were found at the wavelength 445 nm and 535 nm respectively.Dual-wavelength spectrophotometric measurements were made with 535 nm as measuring wavelength and 445 nm as reference wavelength.Beer′s law was held in the range of 0-12 μg of Zn(Ⅱ) per 25 mL of solution,with an apparent molar absorptivity of 1.88×105L·mol-1·cm-1.In its application to the analysis of 2 kinds of plant samples,values of RSD′s (n=6) obtained were less than 2.5%,and results of recovery test were in the range of 99.6%-100.4%.