Ore residue after mineral processing or smelting is called slag. The slag containing SiO₂ is acid slag, and Al₂O₃ and CaO are mostly alkaline slag. The activity of alkaline slag is higher than that of acid slag. Slag has certain water hardness and is not suitable for long-term storage. Slag powder is the raw material of blast furnace slag in metallurgical industry. It is an indispensable inorganic mineral admixture for high strength and high performance concrete. It is a high-tech product of building materials. Using slag powder as concrete admixture can not only replace cement equally and reduce the cost of concrete, but also make full use of blast furnace slag. It saves a lot of precious resources that can not be regenerated for the country and alleviates the shortage of cement supply in time.