Abstract: The dynamics of a self-balancing one-wheel scooter is analyzed in this paper. The one-wheel scooter is simplified as a two-body system composed of a frame with rider and a wheel. Under the nonholonomic constraint conditions of pure rolling of the wheel, the dynamic equations of the system are derived by use of the theorem of angular momentum. The acceleration and deceleration, the turning motion of the scooter, and the standing stability of the rider are examined theoretically. The stability criteria of self-balancing procedure by control system are derived.