The feeder terminal unit controls the distribution network actively when a fault occurs in the active distribution network, it requires a simple and effective control algorithm. So a fault location method based on current polarity comparison for active distribution network is proposed. In this method, the feeder terminal unit detects fault currents in real time, the abrupt change moment is taken as the fault starting moment. The fault current of half cycle is stored from the fault starting moment and its polarity value is calculated. Fault location is realized by comparing the fault current polarity of adjacent detection points. Simulation and field verification results show that the proposed method can achieve accurate fault location under phase-to-phase short-circuit faults and single-phase-to-ground faults in active distribution network. This work is supported by National Natural Science Foundation of China (No. 61472227 and No. 61403236), Science and Technology Development Plan of Shandong Provincial Education Department (No. J15LN10), and Yantai Science and Technology Plan (No. 2016ZH055).