Abstract-In this research, in order to optimize casting design of an automobile part (Housing), Computer Aided Engineering (CAE) was performed by using the simulation software (AnyCasting). The simulation results were analyzed and compared with the several casting designs. During the filling process, internal porosities caused by air entrap were predicted and reduced remarkably by the modification of the gate system and the configuration of overflows. With the solidification analysis, internal porosities caused by the solidification shrinkage were predicted and reduced by the modification of the gate system. For making better permanent High Pressure Die Casting (HPDC) mold, some vacuum systems are proposed in order to reduce internal porosities caused by the filling process.