This study aimed to create a multi-cavity and non-uniform thickness die casting for flowing balance. The die casting processes involved a hot-chamber die casting experiment and computer aided simulation to explore the flowing condition of the molten metal in the metal molding process. Computer-aided mould flow analysis software FLOW 3D V9.2 was applied to simulate the filling stage of zinc alloy in the mould cavities. The design parameters of the mould included four variables relating to the gate: width, position, shape, and thickness of cross-section. Analysis results shows that the primary goals of balance design include two things: (1) the flowing path of molten metal was shortest; (2) the mould cavity was easiest to fill with molten metal. The flowing balance design used analysis software to simulate the flowing condition of the air, which produced an air trap. The melting metal motive force pushed air into the slug well in order to reduce the production of pores. The experiment confirms the actual flowing situation of zinc alloy with a nearly 95% accuracy.