Abstract: This study focuses on the guide coupling of the core transmission component in construction machinery. To address the defects such as shrinkage porosity and gas holes that easily occur during the casting process, which lead to insufficient fatigue life, the filling and solidification processes of the casting under pouring conditions of 1550 °C was simulated using ProCAST software. Based on the analysis of temperature distribution, flow patterns, and defect distribution characteristics, the gating system was optimized twice, resulting in an increase in the casting process yield from 64.9% to 68.7%. The results demonstrate that the optimized process achieved stable filling and effective shrinkage compensation, significantly improving internal casting quality. Critical areas exhibited no shrinkage cavity defects, enabling efficient dual-part production from a single mold cavity. Combining electric arc furnace melting with quenching and tempering heat treatment yielded castings with dense microstructure and qualified mechanical properties. This study provides an effective methodology for process optimization and quality control of similar complex structural castings.