Solar radiation pressure is the main driving force and error source for precision orbit determination of navigation satellites. It is proportional to the solar irradiance, which is the “sun constant”. In regular calculation, the “solar constant” is regard as a constant. However, due to the existence of sunspots, flares, etc., the solar constant is not fixed, the change in the year is about 1%. To investigate the variation of solar irradiance, we use interpolation and average segment modeling of total solar irradiance data of SORCE, establishing variance solar radiation pressure (VARSRP) model and average solar radiation pressure (AVESRP) model based on the built solar pressure model (SRPM) (constant model). According to observation data of global positioning system (GPS) and Beidou system (BDS) in 2015 and comparing the solar pressure acceleration of VARSRP, AVESRP and SRPM, the magnitude of change can reach . In addition, according to the satellite precise orbit determination, for GPS satellites, the results of VARSRP and AVESRP are slightly smaller than those of the SRPM model, and the improvement is between 0.1 to 0.5 mm. For geosynchronous orbit (GEO) satellites of BDS, The AVESRP and VARSRP have an improvement of 3.5 mm and 4.0 mm, respectively, based on overlapping arc, and SLR check results show the AVESRP model and the VARSRP model is improved by 2.3 mm and 3.5 mm, respectively. Moreover, the change of inclined geosynchronous orbit (IGSO) satellites and medium earth orbit (MEO) satellites is relatively small, and the improvement is smaller than 0.5 mm.