Abstract: In recent years, there are more and more ATC surveillance equipment in our country, but the quality of its output data cannot be effectively monitored. Low-quality surveillance data will cause the instability of the ATC system and bring hidden trouble to the safe operation of air traffic control. Based on the analysis of surveillance data, we develop a set of multi-source surveillance data quality monitoring system based on GDI+ technology and Mercator projection. The system has real-time display, storage and playback functions, which can monitor data quality from twelve aspects. The practical application shows that the system can not only find the abnormality of the surveillance data in time, but also lock the fault range of the equipment, which provides important support for quickly solving the equipment fault.