Abstract: Conventional agricultural traveling wheels are prone to severe subsidence, continuous slippage and insufficient traction performance when operating on muddy, loose and waterlogged paddy field soil. These inherent technical defects seriously reduce the running stability and operational efficiency of field agricultural machinery, cause serious power loss and unnecessary energy consumption, and greatly restrict the operational flexibility and environmental adaptability of farming equipment in complex wet and soft tillage environments. To solve these prevalent and urgent practical engineering problems in paddy field farming, this study proposes and designs an innovative variable-area anti-subsidence bionic walking wheel specially adapted for paddy field operation based on mature engineering bionic theories and advanced bionic design techniques. Taking the unique physical structure, flexible deformation characteristics and adaptive dynamic movement posture of mallard webbed feet living in wetland environments as the bionic prototype, the newly developed walking wheel is capable of dynamically adjusting its contact area with soil in real time during rotating operation, so as to actively adapt to the complex and variable mechanical properties of different paddy field soil layers. A professional and dedicated wheel-soil kinematics and mechanical test platform was independently built to carry out standardized and controlled comparative performance experiments. Two typical agricultural soil types widely distributed in farmland areas, namely sandy soil with three continuous gradient moisture contents and ordinary farmland soil with four different moisture levels, were selected as test media to fully simulate diverse actual field working conditions and verify the wheel’s universal adaptability. Three typical structural forms of bionic walking wheels, including the variable-area adaptive type, fully expanded webbed type and fully closed webbed type, were tested and compared in this research. Core performance evaluation parameters such as driving torque, soil subsidence depth and effective forward displacement were systematically measured, recorded and analyzed to clarify the internal influence mechanism of soil moisture content and wheel structural state on the comprehensive traction performance of walking wheels. Experimental results indicate that soil moisture content and wheel structural form exert significant interactive coupling influences on the overall working performance, anti-subsidence capacity and traction stability of the walking wheel. The novel variable-area bionic walking wheel presents the best comprehensive performance and environmental adaptability under all matched test conditions. Compared with the other two traditional webbed wheel structures, its maximum drawbar pull and traction efficiency are significantly improved by 50% and 27.7%, respectively. The influence of soil moisture exhibits distinct medium-dependent characteristics: increasing moisture content effectively enhances the traction performance in loose sand while obviously weakening the traction capacity and running stability in cohesive farmland soil. Further discrete element simulation deeply reveals the wheel-soil interaction mechanism, confirming that the superior anti-subsidence and high-traction performance is attributed to its unique adaptive motion strategy of expanding the contact area while touching soil and closing the structure while lifting off. A mathematical correlation model between traction efficiency and slip ratio is established, and the optimal slip ratio ranges suitable for different soil environments are quantitatively clarified. This study provides a solid theoretical basis and valuable technical reference for the bionic design and performance optimization of high-performance paddy field walking devices, which can effectively improve the working efficiency and complex terrain adaptability of modern agricultural machinery in various wet soft soil environments.