Cylinder heads are generally cast by high-quality gray cast iron or alloy cast iron, and aluminum alloy cylinder heads are mostly used in gasoline engines for cars. Aluminum alloy has good thermal conductivity, which is conducive to improve the compression ratio of the engine. Secondly, it has excellent casting performance and is suitable for casting parts with complex structure. However, attention must be paid to the cooling of aluminum alloy cylinder head, and the temperature of its bottom plane must be controlled below 300 ℃. Otherwise, overheating of the bottom plane will produce plastic deformation and warpage.