Large power system interconnection has brought new challenges to operation safety and stability of power system， so it is important to construct power system real time dynamic monitoring system. A type of power system real time dynamic monitoring unit（RTDMU） is described. In order to improve system reliability and anti-jamming， RTDMU is adopted full embedded design. The high accuracy location technology can commendably adapt to the ranging error due to the variation of line parameters. RTDMU comprises synchrophasor， fault data recording， real time dynamic monitoring and process recording， providing reliable data for power system dynamic safety and stability analysis and important data sources for analysis of the ultra-long， large-scale and developing fault.