Abstract: The RV reducers are commonly used in the mechanical arms of industrial robots; due to the limited space within these mechanical arms, the volume optimization of RV reducers has become a key research aspect in the field of industrial robots. In this paper, focusing on the RV-250 type reducer, addressing its structural rationalization design issues, the optimization theory is applied with the reducer's volume and transmission efficiency as the optimization objective functions; a weighted method is used to convert the multi-objective problem into a single objective function. Then, the constraint conditions are established based on the application context. Finally, the particle swarm optimization algorithm is employed to obtain the optimal solution for the RV reducer's design. The optimization results have achieved the rationalization design objectives of the RV reducer. It provides a relevant reference for study on optimization design of the RV reducer.