The cooling circuit should be properly designed for maximum part quality and shortest cycle time. The best way to insure the part quality in terms of cooling circuit is to design an optimum cooling circuit in the part design step. It is desirable to keep the optimum cooling circuit as intact as possible even in the mold design step. In this work, we proposed a new way to install cooling channels and baffle tubes in a mold for large automotive parts such as bumpers and instrument panels. Instead of conventional gradient method, a surrogate model method was used to optimize the cooling circuit for minimizing the temperature deviation over the part. As the surrogate model a response surface of quadratic form was applied. To supply the sampling points to the regression, the face-centered central composite design (FCCD) and the Box-Behnken design (BBD) were tried, and FCCD produced a slight better result. The temperature distribution by the optimized cooling circuit showed a good agreement with the normal distribution. The whole optimization process was done in a proper amount of running time, which means the optimizer can be utilized as a design tool in the part design step for the automatic generation of cooling circuit. The optimized result showed sufficiently low temperature deviation over the part.