Abstract: ［Objective］ To ensure that railway coupler knuckles meet strict mechanical performance requirements and to overcome the limitations of traditional casting and open-die forging processes in terms of forming quality and process complexity, it is aimed to explore a more efficient and quality-controlled manufacturing process. ［Method］ Taking the railway freight train coupler knuckle as research object, a closed-die forging process with a preforming transition is designed and implemented. The rigid-viscoplastic finite element method is used for an in-depth numerical simulation of the closed-die forging process to analyze potential defect types and temperature field distribution characteristics during the forging process. The specific impact of the initial preheating temperature of both the forging and the die on forming quality is studied, with the forging filling rate as the core evaluation criterion, and the optimized process parameters are obtained through numerical analysis. On this basis, the closed-die forging process is further refined by considering detailed metal flow characteristics and the specific locations and causes of forming defects during the forging process. A validation test is then conducted using the adjusted optimized process, followed by a comprehensive error analysis of the final forging. ［Result & Conclusion］ The optimized closed-die forging process significantly improves the forming quality of the forged coupler knuckle, with uniform overall deviation distribution, good filling, high surface smoothness, and no forming defects are observed. The numerical simulation results are highly consistent with the experimental results, confirming the accuracy of the numerical model. The process improvements are proved effective, yielding high-quality forgings that fully meet actual production requirements.