In this paper, the standard zinc coloring reagent and zinc color reaction result in water-insoluble flocculent complex. In addition, the absorbance was measured by spectrophotometer, the characteristic spectrum and the absorbance were studied, and the mathematical model was established between the concentration and the absorbance of characteristic wavelength. In this paper, color reagent mainly makes complexing reaction with zinc, copper, cadmium, nickel ion, so this study mainly explores the absorbance of four kinds of ions, such as high concentration and low concentration. Finally, through capturing the relationship between the concentration of zinc ions and the absorbance of the zinc ion, and getting the relationship between the concentration of zinc ions and the absorbance of the zinc ion as well as the absorbance of the four kinds of ions with four wavelengths, the relationship between the absorbance and the total absorbance of the zinc ion is given. During the experiment, the color reaction can meet the requirements of spectrophotometry, which is mainly because of the nature of the reagent, while the color reaction conditions are also essential. In the color reaction process, it is mainly zinc ions and zinc coloring agent complexation react to form complex ions, and flocculent complex. The ion is generally stable, but there is also ionization balance in the aqueous solution, that is when the color conditions change, the formation of complex ions may also occur in the decomposition of complex ions, thus affecting the degree of complex reaction . Color conditions include the amount of reagent, PH value, reaction temperature, color time, the salinity of the solution and turbidity. In conclusion, this paper focuses on the salinity of the solution to be measured on the measurement of zinc ion concentration, and gives the influence rule and calibration model through experiments.