The family mold casting have advantages which are able to make products with different shapes and dimensions simultaneously in a single mold. In this study, the design of the 4 cavity rotor family mold was used by "Anycasting" software, the defects occurred during die casting were predicted and suggested the best optimization conditions for sound products. The result of the experiment were that the optimum overflow design was needed for gas emission and control of residual oxides. It was clear that the defects positions formed by diecasting were agreed with nearly them predicted by simulation.