Research on the scheme to prevent zone III distance protection from incorrect operation caused by non-fault overload—the power flow transferring identification method based on DC sensitivity factors is carried out. According to the features of transfer power flow sensitivity factors matrix, the disadvantage of this scheme is proposed which may identify incorrectly due to the only criterion of active power when fault occurs. In order to improve its performance, the criterion of impedance angle is put forward. The concept of power flow transferring characteristics (PFTC) is introduced and is applied to the improved flow transferring identification scheme. The improved scheme can identify non-fault overload reliably and block zone III distance protection to prevent cascading trips effectively. The simulation results of IEEE 10-machine 39-bus system have proved its superiority and practicality.