Abstract:In order to study the high-order ionospheric delay and its influence, we use actual measurement data of IGS combined with specific experiments to discuss the geomagnetic model, TEC data model, GPS frequency and station distribution and other factors. We analyze the delay of high-order terms of the ionosphere and their influence on the baseline under different TEC acquisition methods and geomagnetic model processing modes. Experimental results show that the TEC obtained by different methods is a key factor affecting high-order ionospheric delay, its influence on carrier phase observations is up to 10.0 mm, and its impact on baseline is even up to cm level. Geomagnetic field is a secondary factor of high-order ionospheric delay. The influence on carrier phase and baseline is at the mm level; high-order ionospheric delay is related to the station area, showing systematic deviation in mid-latitudes, while high-order ionospheric delay near the equator shows occasional characteristics, and its main influence on the baseline is related to the distance and azimuth of the baseline.