Using the blocking protection guarantees the selectivity between multilevel protections of distribution line and improves the power distribution reliability. But the existing blocking protection methods need the cooperation of outlet circuit breakers, and are not suitable for the system with branch lines and network topology with dynamic change. A novel method of bi-direction blocking protection based on distribution automation system is proposed. In this method the master station identifies the position of every FTU (Feeder Terminal Unit) according to the network topology, and mainly determines the FTU adjacent to outlet circuit breakers whether locates at the head or the end of line. The FTU which recognizes the fault current sends blocking signal to their adjacent FTU, and then the FTU of different roles determines the fault location and clears the fault according to different criterions. This method can clear the fault of tie lines and branch lines rapidly and accurately. The selectivity and rapidity are verified by static model test analysis.