In order to improve the bearing capacity of ship-mounted universal coupling,a certain type of cross-shaft universal coupling fork was taken as the research object,and the analysis process of the fork was established by Abaqus. In comprehensive consideration of manufacture, structure and assembly of the original fork, the fork was simplified and a mathematical model of the fork was established. A new method based on particle swarm optimization algorithm was put forward for size optimization of the fork,then an Abaqus script written by Python was used to complete parametric modeling and analysis of the fork. Based on the optimization method,a new type of universal coupling fork was developed and the performance test was carried out. The results show that the method can improve bearing capacity of the fork effectively,providing an example for structural optimization or design of similar products.