In order to utilizefixed series capacitor more reasonably to improve the voltage deviations of the distribution network with weak structure, big radius of power supply and heavy load in the end of long feeder, the multi-objective optimizationmethod is researched on determining the location and size of the fixed series capacitor. A multi-objective model used for optimizing fixed series compensation condensance in the distribution network is built. The objective functions of the model are consisting of the minimum of integral voltage deviation, condensance of series capacitor and active network loss. Based on sensitivity method and the principle reducing the line voltage loss by fixed series capacitor, the candidate line for fixed series capacitor installation and calculate ranges of series compensation condensance are determined. Fast and elitist non-dominated sorting generic algorithm is used to solve the optimization model. The simulation examples validate the feasibility and effectiveness of the method. The results show that the series capacitor of the distribution network can effectively improve voltage quality and reduce active network losses.