Die design of die casting is composed of selection of cast alloy, design of die casting product, runner design and gate design, etc. In reality, however, die design of die casting has been performed by trial and error method, which cause economic and financial loss. Nowadays, several FEM(finite element method) and FDM(finite difference method) codes have been developed to analyze process of die casting, but this is just confined to an offer of limited information for die design of die casting. In this study, die design system for gate of die casting process has been developed to present algorithm for automation of die design, especially runner-gate system. In addition, specific rules for runner-gate system have been presented to avoid too many trials and errors with expensive equipment. It is possible for engineers to make automatic and efficient die design of die casting and it will result in reduction of expense and time to be required.