The invention relates to the technical field of printing and dyeing control, in particular to a decolorization control system for denim fabric. Color parameters are obtained through spectrum analysis,so that the decolorization treatment of the denim fabric is controlled. The decolorization and laser carving treatment of printing patterns on laser engraving areas are controlled according to the color parameters obtained through spectrum analysis and printing pattern models, thereby achieving the decolorization and appearance effect on the denim fabric and the printing pattern and avoiding theproblems that in the prior art, excessive decolorization or insufficient decolorization due to the fact that adding the same time and the same ozone dosage without distinguishing types of fabric and printing content in a decolorization treatment process. Ozone is used for decolorization treatment, so that decolorized fibers do not need to be cleaned, decolorization and drying are enough, and waterresources are saved. No chemical raw materials are used, so as to avoid environmental pollution.