Abstract: A gear matching design method that comprehensively considers power, speed, and modulus parameters is proposed to optimize the load sharing performance of the splitting and confluence transmission system and suppress geometric interference. Based on interference conditions, transmission ratio constraints, and coaxiality criteria, a mathematical relationship model for multi-stage transmission systems is established, and the gear matching calculation process is systematically explained.The verification through numerical examples shows that the rounding error of gear module has a significant impact on the load sharing performance. Reducing the error can effectively meet the interference conditions and improve the uniformity of load distribution.By combining 3D modeling and interference analysis, 6 sets of optimal gear matching schemes are selected, and their effectiveness is verified through dynamic testing on an experiment bench. The results show that after optimization, the dynamic load factor of the system decreased by 3.33%, and the overall volume decreased by 16.01%, significantly improving the compactness and reliability of the transmission. This study provides theoretical support for the lightweight design and performance improvement of power transmission systems for high mobility helicopters.