As the operational satellites of China’s FengYun-3 meteorological satellites series, FengYun-3C (FY-3C) and FengYun-3D (FY-3D) are launched in 2013 and 2017 respectively. For the purpose of occultation observation and positioning, FY-3C is equipped with a BDS and GPS dual-system receiver, GNSS Occultation Sounder (GNOS) instrument while FY-3D carries an enhanced one, which give us a great opportunity to investigate the enhancement of onboard data for the GNSS orbits, especially for the BDS constellation. Using FY-3C and FY-3D onboard data as well as global station observations, we processed the integrated precise orbit determination (IPOD) with FY-3C, FY-3D and both of FY-3C and FY-3D respectively. The overlap comparison result shows that compared with FY-3C, FY-3D presents a superior enhancement to GNSS satellites orbits, which can be owing to the more available onboard BDS and GPS data for FY-3D. The overlap difference of GPS, BDS GEO, IGSO and MEO is reduced by 3%, 52%, 2% and 6% respectively when FY-3D data are introduced into the IPOD process replacing that of FY-3C. As expect, the integrated processing of FY-3D and FY-3C onboard data can further improve both BDS and GPS orbit precision. Compared to the IPOD with only FY-3D involved, the orbit precision of GPS, BDS GEO, IGSO and MEO for the IPOD with FY-3C and FY-3D can be improved by (10%, 4%, 21%, 19%), which demonstrates that the more onboard observations can make more contributions to BDS and GPS orbits even with the global network.