The dynamic characteristic analysis of AC Servomotor which is controlled by AC square voltage is studied in this paper. Although nonconventional sampling method is proved to be effective in controlling the output by changing square voltage width, it is difficult to attack the problem by the classical method. In order to solve the problem easily, the state transition method is introduced in this paper. One of the important advantages of this approach is that the analysis procedure is of a recursive nature and this can readily be programed on a digital computer to yield a quick, accurate solution. Various output characteristics are identified by changing the square voltage width and much improved output response is obtained when the square voltage widths are modulated for the initial period.