The preheating of the mold before pouring mainly affects the heat exchange effect between the mold and the melt during the pouring process, and delays the cooling time of the melt so that it has sufficient power for mold filling. When the mold is not preheated or the preheating temperature is too low, the melt will transfer a large amount of heat energy to the mold, and the cooling speed will become faster, which is easy to cause insufficient filling power. In other words, it is easy to form solidification defects such as insufficient pouring and cold isolation; in addition, the mold with lower preheating temperature may also have dangerous effects such as thermal expansion and cracks under the action of high temperature melt. When the preheating temperature of the mold is too high, the melt has good fluidity, but it will cause unfavorable conditions such as longer solidification and forming time, excessive dendrite growth and precipitation of the second phase; the mold will also be deformed due to excessive heating , decrease in strength, etc. Whether the mold needs to be preheated and the size range of the preheating temperature need to be reasonably formulated according to the material characteristics and test conclusions.