The lost foam casting is different from the wood casting. When the casting is poured, the molten iron occupies the position of the lost mold, and the lost mold burns to become a casting. With the lost foam machine tool casting, the amount of gas generated when burning the lost mold is inevitably considered. The amount of gas generated depends on whether the coating dries and the density of the lost mold. Therefore, reducing the amount of gas generated by the lost mold machine tool casting starts from the following two aspects. The foam model must be dried before coating. Each batch of foam model should now check the weight change of the drying process and make a graph of the baking weight change. The coating can be applied only when the weight is no longer changed. The density of the foam model should be small. Under the premise of ensuring the surface quality of the foam and ensuring the strength of the model, the foam should be made as light as possible to reduce the amount of gas generated during pouring.