In the framework of the modern smart grid technologies,the optimal distribution of voltage sag monitoring device is an important research field in the study of power quality monitoring terminal.The installation location and monitoring scope of the monitoring device are described respectively based on the position vector and monitoring area matrix of monitoring device.The mathematical model of the optimal distribution of monitoring device is constructed by considering the specific requirements for distribution of monitoring device,and a 0-1 integer programming is proposed corresponding to the optimal model.Finally,the proposed method is applied to an IEEE-30 network to determine the optimal distribution of voltage sag monitoring device in the whole network,of which the correctness and validity is further analyzed.