In order to solve the problems that the positioning information of the ADS-B transmitter is mainly taken from GPS and the limited distance of the transmission link, the technology of ADS-B monitoring based on “BeiDou” is researched. After a in-depth study on the ADS-B message protocol and making the “BeiDou” communication as a supplementary transmission link to ADS-B, the airborne monitoring terminal system using the “BeiDou” positioning source is designed and the seamless navigation and surveillance technology is studied for aircrafts. RX1E electric general aircraft and the established monitoring center system are used to test and verify the ADS-B and “BeiDou” transmissions of airborne terminal. The results show that the data transmission links realize wide-area surveillance of low-altitude airspace navigable aircraft, and the flight situation information sent by the airborne terminal realize the monitoring center’s online situation awareness of low-altitude aircraft. The research results provide a technical reference for serving the operational safety of China's general aviation aircraft and improving the informationization level of low altitude airspace management.