The power electronic devices which are widely used in the dense new energy areas are easy to produce a large number of subsynchronous harmonic, which leads to the subsynchronous oscillation in the power system. In order to monitor and collect subsynchronous oscillation information in real time to study the generation mechanism and control methods of oscillation, this paper proposes the deployment principle of PMU and SMU substations based on the subsynchronous harmonic propagation path, and connects the substations with the WAMS main station to build a wide area subsynchronous oscillation monitoring system. Finally, when the system is applied to Hami area of Xinjiang, the system can monitor a large number of subsynchronous oscillation information accurately and effectively, and intuitively display the dynamic development process of subsynchronous oscillation, so as to provide data basis for further research. This work is supported by National Natural Science Foundation of China (No. 51667018 and No. 51367015) and State Grid Xinjiang Electric Power Company (No. SGXJ0000DKJS1440234).