Affected by external force and lightning strike, the high voltage overhead line is easy to be broken. But the current line protection device can only identify the line break fault accurately after the fault line landing. In view of the problem that there is no protection algorithm especially for line break fault, a novel protection based on two-terminal information is presented in this paper. According to the voltage and current information on both sides, the calculated voltage drop and the measured voltage drop of each phase line are calculated respectively. Then the line break fault is quickly and reliably determined by calculating the magnitude of the difference of the two voltage drops and the magnitude of the line current. Finally, the simulation results verify the effectiveness of the protection algorithm in PSCAD/EMTDC. This work is supported by National Natural Science Foundation of China (No. 51477061).