We suggest a Moire deflectometry for measuring the object with synchronous change of phase, displacement- Moire deflectometry. When the object is rotating or wiggling, the displacement of Moire fringe indicates the angle of axis, and the stability of fringe indicates coincidence of the beam axis. This method is simple and the automeasurment is easy with high accuracy. In this paper the theory, measuring accuracy and some applications of this method are introduced.