The invention discloses a four-legged wheeled mobile robot and belongs to the field of mobile robots. An inertial measuring device is fixed in the center position of the upper surface of a vehicle body frame and can be used for measuring the posture of the robot in the moving process; four supporting legs are symmetrically mounted on the two sides of the vehicle body frame; each supporting leg is composed of a linear guiding mechanism, a swinging mechanism and a moving wheel; rapid movement of the four-legged wheeled mobile robot on the flat ground is achieved through the four moving wheels; and movement of the robot on the rugged ground is achieved through four swinging legs which are all composed of the linear guiding mechanisms and the swinging mechanisms. According to the robot, effective combination of fast moving and obstacle crossing is achieved, namely the movement speed on the flat ground can be guaranteed, and the very good obstacle crossing capacity is achieved.