A solvent method for extracting sulfur from waste residue or sludge through flue gas desulfurization relates to a method for extracting the sulfur from the waste residues or the waste sludge. The invention discloses two methods for extracting the sulfur from wastes. In the method, the high-quality sulfur is recycled from the waste residue or the waste sludge through the flue gas desulfurization and biological treatment; a solid-liquid mixture (or is dehydrated and dried to be a drysolid) is added to a solvent-carbon bisulfide (or tetracarp) according to the drysolid and the mass ratio of the solvent of 1:1-1:5; at the mixture temperature of 10 to 45 DEG C (the tetracarp temperature of 20 to 90 DEG C), the mixture is stirred and extracted for 5min to 3h; then the extracted solid-liquid mixture is filtered at a constant temperature; then after cooling crystallization or evaporation crystallization, a filter liquor is filtered to obtain solid sulfur; and then the solid sulfur is dried toobtain a sulfur product. The invention has the advantages that the method is simple and practical, and the solvent can be recycled; and under the condition of lower energy consumption, the sulfur product with higher purity can be obtained, so as to realize the reasonable utilization of the wastes.