The invention discloses a leaf sucking machine and a motor axle steering device thereof. The motor axle steering device comprises an operating handle, a machine frame, driving rear wheels, a motor axle and a braking hub, wherein the motor axle and the braking hub are fixed on the stander, the driving rear wheels are fixed on the braking hub of the motor axle, and a user can control the operating handle to trigger the braking hub so as to control the rotation of the driving rear wheels. The leaf sucking machine comprises the motor axle steering device. The leaf sucking machine and the motor axle steering device have the advantages that the structures are simple, the occupied areas are small, and the costs are low; and the actions of left and right driving wheels can be controlled, and the left steering and the right steering can be realized, so that the labor of an operator during the operation is saved, and the physical fatigue caused by the manual steering is greatly reduced.