The invention provides a blast furnace gun mud added with SiAlON synthesized throughcoal ash and a preparation method of the blast furnace gun mud. The gun mud is characterized in that industrial corundum particles and fine powder, silicon carbide particles and fine powder, coke powder, clay fine powder and asphalt powder are adopted and used as the main raw materials; proper SiAlON fine powder which is synthesized by the coal ash discharged by a coal fired power plant is added; and the oil tar is used as a bonding agent. The blast furnace gun mud has the beneficial effects that: 1, the prepared gun mud is excellent in the following performances, high plasticity, high bonding performance, excellent sintering performance, proper air porosity, low high-temperature volume shrinkage, high resistance to slag-iron erosion, high flushing performance, and high open performance; 2, the industrial waste that is coal ash is used as the synthetic raw material of the adopted SiAlON material, so that the cost of the raw material is low, and as a result, the production cost of the gun mud is relatively low; 3, the industrial waste that is the coal ash is used as the raw material for synthesizing the SiAlON material, and a novel mode is also provided for comprehensively utilizing the coal ash; and 4, the blast furnace gun mud has important economic benefit and social benefit.