A wheel-legged amphibious mobile robot with a variable attack angle, which belongs to the technical field of robot structure technology. The robot includes three parts: motion unit, body trunk and power unit. As a key structure, the motion unit mainly includes a moving mechanism, a wheel assembly, a telescopic mechanism and a transmission device. The robot drives the telescopic mechanism to reciprocate linearly through a gear and rack set, and pushes “legs” to expand and retract, so as to realize a mutual switching between a wheeled mode and a gait mode. Under transmission of bevel gear set, the blades can rotate at any same angle at the same time, to change the attack angle and realize the steering. The robot provided by the present disclosure can effectively adapt to a complex and harsh amphibious environment, and meet a series of operation requirements such as rapid movement, obstacle climbing, underwater steering.