As modern agriculture expands into complex unstructured environments, including hilly terrain, paddy fields, and wetlands, conventional wheeled and tracked chassis increasingly face poor terrain adaptability, limited obstacle crossing capability, and severe soil compaction. Wheel-legged agricultural chassis combine efficient wheeled mobility with flexible legged obstacle crossing, offering a new approach to balancing operational efficiency with terrain adaptability. This review systematically summarizes the key technologies and recent advances in wheel-legged agricultural machinery chassis. It first analyzes the limitations of conventional mobile platforms and the technical insights provided by transformable wheels and biomimetic legged robots. Existing research is then reviewed in four areas: configuration and lightweight design, motion and posture control, obstacle crossing performance, and multi-sensor perception and autonomous navigation. The application potential and engineering limitations of wheel-legged chassis in hilly farming, protected agriculture, paddy fields and wetlands, and material transport are further examined. Because terrain adaptability relies on additional joints, actuators, sensors, and control systems, a fundamental conflict exists between mobility gains and structural complexity, manufacturing cost, energy consumption, and field reliability over prolonged operation. Future research should prioritize modular structures with fewer degrees of freedom, robust adaptive control, whole-machine energy management, protection against environmental exposure, and prolonged field testing to balance terrain adaptability with engineering practicality.