Millimeter wave imaging techniques for full body scanner is becoming increasingly important to detect concealed body-worn threats. A new configuration of full body scanner is designed in this paper. It utilizes human movement and standing linear array to form a planar synthetic aperture, which basically pertains to inverse synthetic aperture radar. Human movement is controlled by powerwalk, so the velocity of human is known. A three dimensional ISAR imaging algorithm is proposed and system parameters design is also discussed. Imaging result of human point model is given to prove the effectiveness of the proposed method.