Abstract: In this paper, differential flux data of energetic (>2MeV) electron of GOES 6~12 during 1986-2006 are used to obtain the flux variation with season and solar cycle at different phases of geomagnetic storm, which in turn can be used for building a more accurate dynamic spacecraft internal charging model. The results show that for different geomagnetic activities, the worst-case electron flux is lower in the solar maximum year while higher in the solar minimum year; the worst-case electron flux reaches its lowest values near summer and winter solstices, while reaches its peak values near vernal and autumnal equinoxes; the energetic electron flux is usually low when Dst index is small.