In this letter, we proposed three digital beamforming methods based on spaceborne reflector and feed array antenna SAR system. With the proposal and development of reflector and feed array antenna, it is of great importance to study the processing of data received by every feed. By using the large reflector antenna area, wide swath on the ground is easier to obtained and Scan-On-Receive (SCORE) is easier to realize, which improves the system’s signal-to-noise ratio and suppress range ambiguities. This paper establishes an echo signal model based on reflector and feed array antenna SAR system and proposes three DBF methods to realize SCORE operation, then using these echo data to verify the validity of DBF methods.