In order to solve the problems of low utilization rate and poor treatment effect of steel slag， an efficient carbonation method of steel slag using Na₂CO₃ solution as the medium was proposed. The optimal reaction parameters were investigated， the carbonation products and the silica prepared were characterized. The results indicate that by adjusting parameters such as Na₂CO₃ solution concentration， reaction temperature， liquid-solid ratio and reaction time， the maximum carbonation degree of steel slag can reach 78.60%. Silicate phases in the steel slag can be completely carbonized， but the carbonation of calcium present in the RO phase （continuous solid solution mainly composed of FeO and MgO）-silicate phase solid solution in steel slag is limited. The extraction rate of 55.46% for silica can be achieved， with a purity of extracted amorphous silica gel as high as 98.79%. The research result provides a direction for the high-value utilization of steel slag.