As a key component of planetary transmission systems, the ring gear plays an important role in load sharing and influencing the system’s dynamic load factor. The inherent flexibility of the ring gear can significantly compensate for the transmission torque imbalance among planetary gears caused by manufacturing and assembly errors. This paper presents a detailed analysis of the structural characteristics of flexible ring gears. Comparative studies show that flexible ring gears exhibit superior adaptability compared to conventional ring gear, improving load sharing capacity and reducing dynamic load factors. However, this flexibility also introduces certain drawbacks, such as unbalanced loading, uneven stress distribution, increased amplitude of loaded transmission errors, and structural stress concentrations. The findings offer theoretical insights for optimizing flexible ring gear design and guiding structural improvements in planetary transmission systems.