Abstract:In this paper, based on the STK software, the simulation of the BDS satellite constellation structure in September 2016 is carried out. The average visible satellite number, DOP value and system availability are taken as indexes to evaluate the constellation design structure. After the failure of single satellite and all tilted satellite (IGSO) and geostationary satellite (GEO), the impact of satellite failure on the availability of BDS in mainland China is analyzed. The results show that the latency of the BDS region is weakened by IGSO4 and GEO5 when the threshold is 2.60. Taking the BDS satellite during normal operation of the GDOP region average maximum value (S=2.60) as the system availability threshold, the system availability is decreased by 1.79% and 32.63%. When the threshold is 2S(5.20), 3S(7.80), 4S(10.4), 5S(13.0), the availability of the system can reach 100%. After the failure of GEO as a whole, BDS high-precision positioning can still be partially available, but the availability of BDS system is greatly limited after the failure of IGSO. Therefore, to increase the on-orbit backup of the satellite, we need to focus on the GEO5, IGSO4 satellite backup, and the appropriate increase in the number of IGSO satellites.