At present, Time Division Multiplexing-Multiple Input Multiple Output(TDM-MIMO) technology is mainly adopted to increase the number of virtual antennas to improve the angular resolution in automotive radar. However, when there exists relative motion between the target and the radar, the amount of phase change caused by the Doppler frequency of the moving target during the switching time of different transmitting antennas is coupled to each receiving antenna, resulting in a defocusing effect of the spectrum. This phase change would have effect on the angle estimate of the target. A TDM-MIMO signal model is deduced in this paper. By analyzing the cause of the phase error of the moving target, a phase compensation method is proposed. It is unnecessary for this method to estimate the target speed, and no additional hardware overhead is needed. The simulation experiment and the measured data show that the method can realize normal angle measurement on the moving target with low time complexity.