A method for determining position of a tire pressure monitor equipped on a tire of a vehicle. The method is performed by a controller and comprises: detecting a radial acceleration and a tangential acceleration of the tire; computing a radial-versus-gravity value and a tangent-versus-gravity value based on the radial acceleration, the tangential acceleration and a gravity acceleration; determining an operating state according to variations of the radial-versus-gravity value and the tangent-versus-gravity value; determining whether the operating state is changed to another operating state; and when the operating state is changed, determining a position of the tire pressure monitor according to a change sequence of the operating states.