Different from the other global navigation satellite system (GNSSs, such as GPS, GLONASS and Galileo), BeiDou-2 uses a unique constellation design, which composed of GEO, IGSO and MEO satellites. With the GEO and IGSO satellites, BeiDou-2 can provide best coverage in the Asia-Pacific region and use a small number of satellites to make the regional navigation performance reach the same level as that of GPS. The monitoring stations of BeiDou-2 operational control system is confined to the Chinese mainland, all the stations are located in northern hemisphere, and different attitude control modes are applied to each type of Beidou-2 satellites. All of them pose the challenges of orbit determination of BeiDou satellites (Zhou et al., 2013). In addition, suffered from a nearly-static viewing geometry, GEO satellites exhibit substantial orbit determination error due to high correlation of orbit and clock parameters. In order to make up the disadvantage of limited satellite-tracking ability of regional monitoring stations, and also get the precise satellite clock offsets, an independent time synchronization system is established. In this system, techniques such as L-band two-way radio time transfer (TWTT) and C-band two-way satellite time and frequency transfer (TWSTFT) are used (Zhou et al., 2011).