The invention relates to a method for preparing industrial sodium silicate by using waste copper sulfur tailings. The method is conducted according to the following step procedures and conditions: performing flotation to remove impurities: adjusting the PH value of copper tailing slurry, adding ammonium dibutyl dithiophosphate, stirring, adding second oil, performing flotation to remove impurities to obtain tailing slurry 1, adding lauryl amine and sodium oleate, stirring, performing reverse flotation to remove impurities such as dickite and alunite to obtain tailing slurry 2, and performing solid liquid separation to obtain quartz concentrate 1; roasting: adding a carbon powder and sodium chloride, mixing uniformly and roasting to obtain roasting clinker; performing acid leaching to remove impurities: feeding the roasting clinker into an acid leaching system, enabling copper, iron and the like in the roasting clinker to leach out, performing solid liquid separation to obtain a leaching liquid and acid leach residue, grading the acid leaching residue to obtain overflow and underflow, and performing solid liquid separation and drying on the underflow to obtain quartz concentrate 2; melting at a high temperature: adding the quartz concentrate 2 into sodium carbonate, mixing uniformly, melting and pouring to obtain a solid sodium silicate product. The method has the advantages of simplicity in process operation, high in practicability, environmental friendliness, easiness in industrialization and the like, and is suitable for comprehensive utilization of mineral resources.