Magnesium smelting slag has a large stock and serious pollution, so it is important and significant to make resource utilization according to its characteristics. In this paper, magnesium smelting slag is used as the main raw material and coal gangue as the auxiliary material, and multi-purpose magnesium smelting slag sintered materials are prepared by high temperature solid phase sintering. The effects of coal gangue dosage, sintering temperature, constant temperature time and molding pressure on the properties of magnesium smelting slag sintered materials are studied, and its mineral composition and reaction mechanism are analyzed by XRD, TG-DSC and other methods. The results show that, on the premise of making full use of magnesium smelting slag, the best preparation parameters of magnesium smelting slag sintered material are as follows: coal gangue content 30%, sintering temperature 1 180 ℃, constant temperature time 2 h, and molding pressure 30 MPa. During the firing process, some minerals are decomposed to form new crystalline substances. The raw materials, such as dicalcium silicate, tricalcium silicate and kaolinite, are decomposed, and cacoslasite, rankinite and melilite are formed. The prepared magnesium smelting slag sintered material has excellent physical and chemical properties, and can be used as sintered brick, ceramsite and other materials.