Abstract: Steel slag is the main solid waste in the steelmaking process, the comprehensive utilization rate of only 30%, resulting in a large amount of resource waste and serious damage to the ecological environment. The optimal utilization of steel slag is to return to the steelmaking process for reuse, but since there is no suitable phosphorus outflow pathway in this process, it leads to the phosphorus element being in a constant state of enrichment throughout the production process, making it difficult to realize the efficient utilization of steel slag. At the same time phosphorus, which is vital to agriculture and industry, is a non-renewable resource, while phosphorus in steel slag is a suitable secondary resource. After separating phosphorus from steel slag, it can be utilized in the phosphorus chemical industry, and the tailings can be reused in metallurgical plants. This paper reviews: (1) Sources and properties of steel slag; (2) Current status of steel slag treatment and utilization at home and abroad; (3) Phosphorus enrichment and separation technology in steel slag. In addition, the economics of phosphorus recovery from steel slag is described, and the technology of full utilization of steel slag in hot state recycling is proposed. The application of new steel slag treatment process and hot state full utilization technology will promote the greening of metallurgical industry.