Considering the environmental pollution by the colored waste, the need for nanostructured materials is self-evident. Hence, in this research, the decolorization property of the ZnO/SnO2 nanocomposite was investigated. To produce the desired nanocomposite, the co-precipitation method was used. The desired nanocomposite characterization was performed by PSA, FT-IR, XRD, and SEM, where the nanocomposite size was about 15 nm. The effect of several parameters such as the initial wastewater concentration and the amount of catalyst and time were examined. The nanocomposite particles size reduction due to an increase in the nanocomposites surface area increased the amount of decolorization. In all the experiments the dye removal rate was 100% and the difference pertained to the complete removal time of the dye. It is noteworthy that a decrease in the methylene-blue concentration in the range of the tested concentrations reduced the decolorization and by increasing the amount of nanocomposite tested in the range of the values, a decline was observed in decolorization.