Abstract: Polygonatum, a perennial herb traditionally used in Chinese medicine, exhibits substantial nutritional and therapeutic value, leading to its widespread adoption as a high-value understory crop within China’s agroforestry systems. The Polygonatum serves as the principal medicinal component, whereas the fibrous roots are nutritionally inferior and often interfere with downstream processing, making debearding an essential preprocessing step. Conventional mechanical debearding methods, however, suffer from notable shortcomings including limited throughput, inadequate root removal, and high physical damage to rhizomes, which collectively hinder the scalability required by the growing industrial demand. To address these technical constraints, this study introduces an integrated “drying pretreatment followed by mechanical brushing” technology and develops a novel horizontal hexagonal-tumbling debearding device tailored for Polygonatum processing. The apparatus comprises several core components: a rigid frame, support rollers, an independent cage driving system with motor, a hexagonal rotating cage, an internal counter-rotating Stripping roller assembly with its dedicated drive, a removable collection bin, a protective dust cover, and a slinding door for operational convenience. During operation, the simultaneous yet opposite rotation of the hexagonal cage and the internal Stripping rollers generates a combined tumbling, impacting, and brushing action on the rhizomes. This multi-mechanical interaction facilitates effective detachment of fibrous roots while minimizing structural injury to the valuable rhizome tissue. Building upon the comprehensive description of the device’s architecture and operational mechanics, a detailed dynamic analysis was conducted to model the motion and force interactions of Polygonatum within the drum. This theoretical investigation informed the rational determination of critical design and operational parameters, prioritizing high debearding efficiency alongside low product damage. To systematically optimize performance, a three-factor, three-level Box-Behnken response surface design was employed, with cage speed, stripping roller speed, and feed rate as independent variables, and shedding rate and breakage rate as key response metrics. Statistical analysis of variance demonstrated that both cage speed and stripping roller speed exerted a highly significant influence on the debearding rate, while the feed rate also presented a significant effect. In contrast, none of the three factors showed a statistically significant impact on the breakage rate within the tested ranges, indicating the design’s inherent effectiveness in minimizing harm. Subsequent response surface analysis further quantified the interaction effects among these operational parameters, revealing how their combinations non-linearly influenced the outcome variables. Numerical optimization identified the ideal operational regime as a cage speed of 6.00 revolutions per minute, a stripping roller speed of 90.2 revolutions per minute, and a feed rate of 7.5 kilograms per minute. Under this optimized parameter set, the predictive models forecasted a shedding rate of 97.05% and a breakage rate of merely 0.96%. Experimental validation through triplicate confirmatory tests yielded average results of 96.83% shedding rate and 1.04% breakage rate, displaying excellent consistency with model predictions and confirming the robustness of the optimization. Comparative assessment clearly indicated that this newly developed device significantly outperforms traditional debearding machinery in terms of both processing effectiveness and product integrity. The findings of this study provide a solid scientific foundation and practical engineering insights for the advancement of specialized, efficient, and gentle processing equipment for Polygonatum and analogous medicinal rhizomes. By enhancing preprocessing quality and efficiency, this research contributes directly to overcoming a key bottleneck in the supply chain, thereby supporting the sustainable scaling, value-added processing, and overall competitiveness of the Polygonatum industry. The proposed methodology—combining pretreatment, innovative mechanical design, dynamic modeling, and statistical optimization—also offers a valuable framework for addressing similar technological challenges in the post-harvest processing of other delicate agricultural and medicinal products.