A kind of gelatin protein copper complex (GPCC for short) was synthesized by us. GPCC acting as catalyst was applied to catalyzed hydrogen peroxide for decolorization of C.I. Reactive Red 24 from simulated dyeing wastewater. The influence of catalyzed hydrogen peroxide by GPCC on the decolorization of C.I. Reactive Red 24 from simulated dyeing wastewater was discussed. The optimum decolorization technology condition was optimized. And the effect of salt on decolorization of C.I. Reactive Red 24 in this catalytic system was also investigated. The results showed that hydrogen peroxide can be catalyzed by GPCC. In the catalytic system, the structure of C.I. Reactive Red 24 can be degraded and a high decolorization rate can be obtained in a wide pH range. In addition, the decolorization percentage and decolorization rate will be further improved when salt is present in the catalytic system.