Abstract: As a key factor in GNSS data processing, the yaw attitude of GNSS satellites is closely connected to the geometrical observable error corrections and the non-conservative forces acted on satellites. The precision ofthe calculated orbit and clock (O & C) products are therefore affected by attitude models of the navigation satellites. In this contribution, observations from about 110 International GNSS Service (IGS) stations with the global distribution in 2013 are used to investigate the impacts of yaw attitude on O & C solutions of GPS and GLONASS satellites. The results demonstrate that the degree of yaw attitude on O & C varies according to the types of these navigation satellites. The orbit accuracy of the GPS BLOCK ⅡA satellites during eclipse season were improved by 17 mm, for GPS BLOCK ⅡF by nearly 5 mm, but the BLOCK ⅡR satellites were hardly affected when yaw attitude corrections are used. Compared to GPS satellites, the impact of yaw attitude on GLONASS O & C is greater, which could reach to 10 mm and 0.034 ns for O & C respectively, when the IGS final orbit and GFZ final clock solutions are taken as references.