The invention discloses a harmless and resource utilization method of steel industry chromium-containing wastewater. The harmless and resource utilization method of the steel industry chromium-containing wastewater comprises the following steps: 1) adding steel rolling system acid-washing waste liquid into the chromium-containing wastewater, reducing Cr<6+> in the chromium-containing wastewater into Cr<3+> by utilizing the acidic environment provided by the acid-washing waste liquid and the Fe<2+> therein, and oxidizing the Fe<2+> into Fe<3+>; 2) adding alkali into the reduced wastewater, neutralizing, enabling the Cr<3+> to generate Cr(OH)3 precipitate and the Fe<3+> to generate Fe(OH)3 precipitate, and performing mud and water separation to obtain sludge containing chromium and iron; 3)performing concentration treatment on the sludge containing chromium and iron to obtain homogenous slurry; and 4) feeding the homogenous slurry into a sintering system, mixing the homogenous slurry and the sintering raw materials according to a certain proportion and sintering to obtain a sintered ore finished product for ironmaking and steelmaking. By the method, up-to-standard discharge of the chromium-containing wastewater is realized and resource utilization of the chromium element in the wastewater is realized.