The invention discloses a method for preparing a cellulose-based macroporous gel compound Cu2O visible-light-driven photocatalyst. The method comprises the following steps: dissolving cellulose into a mixed solution of sodium hydroxide and urea, adding ammonium persulfate for initiation at ordinary temperature after obtaining a transparent cellulose solution, sequentially adding a cross-linking agent of N, N'-methylene-bisacrylamide, acrylic acid and an acrylamide monomer, polymerizing at low temperature, and freeze drying after water washing and extrusion pelletization to obtain cellulose-based macroporous gel; immersing into a copper-bearing water solution until adsorption equilibrium, adding a glucose solution after adding a sodium hydroxide water solution, filtering and taking out solid after water bath reaction, freeze drying after water washing to obtain the cellulose-based macroporous gel compound Cu2O visible-light-driven photocatalyst. The method is simple and stable in property, has high efficiency in removing dye and other organic pollutants, can be reused, and can be applied to treatment of waste water containing organic pollutants in the field of papermaking, dye printing, printing and the like.