Beam synchronization is one of synchronizations for spaceborne parasitic radar system, and this paper mainly analyzes this problem. Firstly, based on characteristics of spaceborne parasitic radar system and combined with scannable antenna and adjustable attitude of micro-satellite, three methods for beam pointing synchronization were presented. Then, beam area synchronization was analyzed, the models of beam area for the transmitting satellite and micro-satellites were established. Finally, the simulation of interferometric cartwheel as an example not only proves that these models are valid, but also indicates that the second method for beam pointing synchronization is much better.