Abstract: Under high-speed relative motion conditions, the echo data acquired by the MIMO radar platform are located in different coordinate systems, resulting in deviations in target shape, position, attitude, and other information, which seriously affects target detection and imaging. This paper adopts a motion compensation method based on Doppler Division Multiple Access-Code Division Multiple Access (DDMA-CDMA) joint orthogonal coding for Doppler velocity estimation in different scenarios. First, a signal model for a two-dimensional array is established, the velocity estimation methods for different scenarios are analyzed, and the constraints for motion compensation are given. Furthermore, to address the problem of complete velocity ambiguity caused by coupling of sampling points from transmit channels of multiple scattering points, the DDMA-CDMA joint orthogonal coding is adopted to extend the maximum unambiguous velocity range. Finally, experimental results show that, compared with traditional DDMA coding, the proposed method extends the maximum unambiguous velocity range by a factor of 7, which is consistent with theoretical values; under high-speed conditions, the compensated 3D point cloud images are clearly focused, and the overlap coverage rate of target contours exceeds 95%, showing high consistency with the real target.