To enhance the adaptability of land-air robots in confined and complex environments, a reconfigurable robot capable of switching among flying, rolling, and crawling locomotion modes was designed, and its performance was investigated through theoretical and experimental analyses. First, an active linkage folding mechanism and a passive planetary gear-based clawed wheel were collaboratively designed to enable rapid and stable mode transitions while ensuring propeller protection and terrain adaptability. Subsequently, the transformation process was theoretically analyzed based on mechanical and kinematic modeling to identify key parameters affecting stability and obstacle-crossing capability. Finally, a prototype was developed, and multimodal transformation and obstacle-crossing experiments were conducted. The experimental results demonstrate that flexible mode switching, robust obstacle-surmounting capability, and environmental adaptability are achieved, thereby verifying the rationality of the structural design and the feasibility of multimodal locomotion.