Abstract:We introduce the basic accuracy assessment theory and method of broadcast ephemeris. We then analyze and compare the short and long-term trends of the broadcast ephemeris accuracy, clock bias accuracy and SISRE accuracy of different types of BDS satellites, using 28-month-long broadcast ephemeris data from January 2013 to April 2015. The results show that the orbital accuracy of GEO satellites is about 1.8 m, and the clock bias accuracy is better than 6 ns. As for the IGSO and MEO satellites, orbital accuracy is better than 1.2 m and clock bias accuracy is better than 4 ns. These results are better than the accuracy of GEO satellites overall. The long-term trend of BDS broadcast ephemeris accuracy indicates that its accuracy has a tendency to improve gradually.