Abstract: The fault characteristics of DC distribution networks are of great complexity. Reliable identification and fast isolation of faults are the main difficulties faced by protection. Aiming at the multi-terminal flexible DC distribution network with current limiting reactors, based on the fault transient voltage characteristics of current limiting reactors, a single terminal transient voltage protection method for DC lines is proposed. According to the difference of transient initial voltage of current limiting reactors, the internal and external faults can be identified. The fault types can be distinguished by the voltage ratio coefficient composed of fault voltage of positive and negative limiting current reactors. According to these characteristics, the fault identification criterion and fault pole selection criterion are proposed. The simulation model of the multi-terminal flexible DC distribution network is established in Simulink platform. The results show that the proposed protection method can quickly identify the fault location and fault type within 0.5 ms and can realize the full-line fast operation only by using single-terminal data. Also, the protection method has a good distinction ability between internal and external faults, does not need to consider communication and double-ended data synchronization, and has good anti-transition resistance and anti-noise interference capabilities.