Weight reduction at wheels is important due to its unsprung mass and the associated reduction of fuel consumption and the better ride-and-handling comfort. Especially in the front of the car, a weight reduction is necessary to ease the critical mass distribution at the front axle and therefore increase driving safety. The casting defects that are caused by molten metal were cold shut formation, entrapment of air, gas, and inclusion. But the control of casting defects has been based on the experience of the foundry engineers. In this paper, computer simulations have been carried out to analyze the flow of molten metal. Using Anycasting software to numerical simulating the process of car wheel molding filling and solidification, materials selecting and casting process characteristics and defects of the parts are studied, the causes of casting defects are analyzed.