The heat treatment process of aluminum casting is divided into three stages: heating, heat preservation and cooling. The whole process of aluminum casting can be described by heating speed, heating temperature, holding time, cooling speed and heat treatment cycle. In each heat treatment process specification, temperature is a very important content. If the temperature measurement is not accurate, the heat treatment process can not be correctly implemented, resulting in the quality of aluminum castings decline or even scrap. The measurement and control of temperature is the key of heat treatment process and also the key factor of deformation. The influence of cooling process after quenching on the deformation of aluminum castings is also a very important cause of deformation. After heat treatment, the thin part always cools faster than the thick part in the cooling process. In order to reduce the deformation and cracking tendency of the transition zone due to stress concentration, the thickness gap and the uniform section of the workpiece should be minimized. After heat treatment, the aluminum casting is processed again. According to the law of casting deformation, aluminum casting manufacturers adopt reverse deformation and shrinkage pre expansion to improve the qualified rate of deformation after quenching.