In the present study, numerical work applying a finite element method (FEM) is used to analyze the characteristics of aluminum (Al) alloy mold for thermal strain control. In the concrete, the temperature distribution on the inside of Al alloy mold, the contraction rate and stress occurred by temperature variations are investigated to predict the accurate measurement variation of Al alloy mold during the cooling process. In addition, the numerical result of the Al alloy mold were compared with those of mild steel mold in order to obtain the improvement and good quality of mold. In the end, the numerical results such as temperature distributions, contraction rate and stress are presented to help to make the effective and the best mold products. Besides, the introduced technique of numerical analysis applying a FEM is very useful and important things in the fracture and damage mechanics, especially needs the accuracy improvement such as Al alloy mold products.