Aiming at the problem of low production efficiency of malleable cast iron connectors in a foundry, this paper developed a casting process of one box and two pieces based on the original casting process of one box and one piece. Combined with the casting process design method of cast iron, the preliminary casting process of the connector was simulated and optimized by ProCAST numerical simulation software, and the production trial was carried out. Considering the insufficient casting defects exposed in the trial production, the causes were analysed through the visual results obtained by simulation. By adjusting the height of the residual indenter, the pouring temperature and the riser position, the casting process of the malleable iron connector is finally determined, which improves the production capacity of the connector in the foundry and makes the qualified rate of the casting reach more than 90%.