As more and more devices sensitive to voltage fluctuation are widely connected to the power grid, the direct and indirect economic losses caused by the faults in the distribution network become more and more serious, which puts forward higher requirement for power supply quality. Accurate location of fault sources is an indispensable step in the treatment of power quality problems. A fault source location method for distribution network based on positive sequence voltage is proposed for fault-type disturbance. Based on the distribution characteristics of positive sequence voltage at each monitoring point when a fault occurs, the information based on monitoring points and the fault distance location model of each branch are established. The concept of similarity index is defined based on the correlation coefficient between Mahalanobis distance and Pearson correlation coefficient, which serves as the objective function to determine the location of the fault source. The genetic algorithm is used to find the optimal fault distance as the location result. The effectiveness and accuracy of the proposed method are verified by PSCAD simulation based on IEEE 14-bus network.