A walk-behind self-propelled machine (100, 200), comprising: a chassis (10, 240); a wheel, configured to support the chassis (10, 240) and rotatable relative to the chassis (10, 240); a drive motor, configured to drive the wheel to rotate; a handle, configured to be operated by a user to push the walk-behind self-propelled machine (100, 200) into motion and comprising two grips (411a, 411b) operative to be held by a left hand and a right hand of the user; a speed adjusting element (42, 142,242), configured to be movable relative to the handle to adjust a rotational speed of the drive motor, and configured to be operated by the user when the user holds one of the two grips (411a, 411b) with a single hand, the speed adjusting element (42, 142, 242) being disposed between the two grips (411a, 411b); and an electromechanical converting device, configured to convert a positional change of the speed adjusting element (42, 142, 242) relative to the handle into an electrical signal for adjusting the rotational speed of the drive motor; wherein the speed adjusting element (42, 142, 242) is movable relative to the handle between a first position and a second position; and wherein the rotational speed of the drive motor when the speed adjusting element (42, 142, 242) is in the first position is greater than the rotational speed of the drive motor when the speed adjusting element (42, 142, 242) is in the second position; characterized in that, the speed adjusting element (42, 142, 242) is rotatably connected to the handle about a central axis, and the speed adjusting element (42, 142, 242) is formed as a ring-shaped component that surrounds the handle. a chassis (10, 240); a wheel, configured to support the chassis (10, 240) and rotatable relative to the chassis (10, 240); a drive motor, configured to drive the wheel to rotate; a handle, configured to be operated by a user to push the walk-behind self-propelled machine (100, 200) into motion and comprising two grips (411a, 411b) operative to be held by a left hand and a right hand of the user; a speed adjusting element (42, 142,242), configured to be movable relative to the handle to adjust a rotational speed of the drive motor, and configured to be operated by the user when the user holds one of the two grips (411a, 411b) with a single hand, the speed adjusting element (42, 142, 242) being disposed between the two grips (411a, 411b); and an electromechanical converting device, configured to convert a positional change of the speed adjusting element (42, 142, 242) relative to the handle into an electrical signal for adjusting the rotational speed of the drive motor; wherein the speed adjusting element (42, 142, 242) is movable relative to the handle between a first position and a second position; and wherein the rotational speed of the drive motor when the speed adjusting element (42, 142, 242) is in the first position is greater than the rotational speed of the drive motor when the speed adjusting element (42, 142, 242) is in the second position; characterized in that, the speed adjusting element (42, 142, 242) is rotatably connected to the handle about a central axis, and the speed adjusting element (42, 142, 242) is formed as a ring-shaped component that surrounds the handle.