Abstract:  With the development of satellite navigation technology, the user demands for the integrity of Global Navigation Satellite System (GNSS) have increased more and more. A ground-based monitoring system can hardly report an alarm message to GNSS users during the valid alarming period due to the satellite-Earth propagation delay. It is beneficial to monitor abnormal events and report the corresponding alarms from orbit. Adopting this approach, which is an important feature for future GNSS integrity monitoring, the time needed to provide an alarm is shorter and the system integrity capability is strengthened. The BeiDou Navigation Satellite System (BDS) new generation satellites have the capabilities of satellite autonomous integrity monitoring (SAIM). This paper presents the technical scheme of SAIM, and proposes the integrity monitoring method of both navigation signals and the clocks onboard. The proposed method was verified through the onboard test on the BDS satellites. In addition, we analyzed the integrity telemetry data from the new generation of BDS satellite, including signal delay, power, carrier phase measurement, correlation peak, consistency of pseudo-code and carrier phase, clock phase and frequency step. The analysis results indicated that the quality of the data on orbit met the requirements, and SAIM could monitor effectively any abnormal change of satellite clocks and navigation signal, generate rapidly an alarm message, and transmit it to the user. The alarm time was less than 6 s through the message, and 2 s through non-standard code (NSC). Finally, we present future opportunities for improving the SAIM technology of BDS.