Abstract: The application of steel slag in building materials was analyzed in allusion to the larger amornt of steel slag but the lower utilization ratio.Steel slag is not better to produce cement or mineral admixture of concrete because of poor grindability,larger fluctuation of chemical and mineral components,poor stability and so on.However,steel slag may be used as aggregate according to alrger rigidity,higher strength and cementitious property,which will solve the supply-demand confliction of aggregates in the production of concrete presently but also improve the engineering performance and lower the construction cost,and as a result,the utilization of steel slag may be high-added-value.