The pivotal technical attribute of planetary gear trains lies in their load distribution characteristics. While theoretical studies on planetary gear trains are well-developed, experimental methodologies for accurately measuring uneven load coefficients are lacking. This paper introduces a novel experimental approach that utilizes fan-shaped segmentation of the sun gear to measure these coefficients effectively. Initially, leveraging the kinematic and architectural peculiarities of these systems, the sun gear is meticulously segmented into fanshaped sections. Subsequently, using planetary gear trains with five and six planetary gears as examples, the experimental protocol comprehensively encompasses sun gear preparation, strain gauge installation, gear wiring, data acquisition, and subsequent processing. Ultimately, the study delves into the influence of torque, rotational velocity, and the count of planetary trains on the uneven load distribution coefficient, thereby furnishing both theoretical and practical insights to underpin the design of planetary gear trains for enhanced operational stability.