It is difficult to locate fault section of distribution network with distributed generation. Aiming at this problem, a fault location algorithm based on sub-network partition is proposed. The algorithm works in three stages:in the first stage, it constructs the topological network description matrix of distribution network; in the second stage, it divides the complex distribution network into several sub-networks, then obtains the directional description matrix and fault information vector of each sub-network, furthermore, establishes the fault location discrimination matrix; in the last stage, it locates the fault section according to the discrimination matrix. The adaptability of a single point fault, fault paths partial and complete overlap of multipoint faults in distribution network is analyzed by case study. The results show the effectiveness of the proposed algorithm. This work is supported by National Natural Science Foundation of China (No.51767023).