[Objective] The research aimed to study Cr wastewater treatment by steel slag.[Method] Steel slag was used as adsorbent to remove Cr from wastewater,and influence factors of the Cr wastewater treatment by steel slag were studied.[Result] Removal rate of Cr(VI) by steel slag was quite low,and the highest removal rate only reached 8.9%.Cr(Ⅲ) removal by steel slag was quite effective.For 50 ml of Cr(VI) solution(100 mg/L),after reduction,0.30 g of steel slag(100 meshes) was added to oscillate for 35 min,and total Cr removal rate was up to 90%.Cr adsorption by steel slag was an exothermal process,and physical adsorption was dominant.Steel slag was suitable for treating acidic Cr wastewater,and its adsorption process on Cr followed Frenndlich isothermal adsorption model.[Conclusion] It could reach the aim of "waste treatment by waste"by using steel slag to treat Cr wastewater.