To increase the receive gain and signaltonoise ratio (SNR) in the SAR signal processing, the technique of digital beam forming (DBF) (scanonreceive, SCORE) can be employed to receive and process echo signal by forming a high gain and sharp beam pattern to receive the pulse echoes. In this paper, the echo signal of each channel on elevation is analyzed firstly, and the method of SARGMTI processing is given and analyzed. On this basis of SARGMTI, this paper presents an algorithm of Ka SARGMTI using DPCA clutter suppression technique to process echoes based on the timevariant weighting DBFSCORE and further presents the block diagram of system realization. Compared with other SARGMTI processing methods, using DBF technique can enhance the system SNR and improve the performance of suppressing clutter. Finally, moving target simulation results validate that using DPCA to process moving target echoes based on DBF is as same as the common echoes, that is, prove its effectiveness of the proposed method.