A wide range of applications has been motivated by the development of millimeter wave (mm.wave) technology. Recently mm.wave spatial chipless RFID has been developed as an alternative method to conventional Chipless RFID technologies. In a spatial based chipless RFID system, the most critical requirement is the resolution of the surface tag which encodes the data. Narrow antenna beam-width is expected to obtain the high resolution. MIMO imaging has been proved as a high-resolution imaging method with a few number of antennas. In this paper, a new spatial chipless RFID reader based on mm.wave technology and MIMO technique is proposed to achieve a high-resolution image, compact design, and fast sensing. The proposed reader could achieve 5-mm resolution image of a 17-bit chipless tag which is the best resolution of a spatial chipless RFID system declared in the literature.