Abstract: Solar radiation is the main source for heating the thermosphere. The change of its intensity can result in the change of Earth’s upper atmospheric density. With the same reason, the difference between the sunlit and shaded area is one of the main reasons for the difference of upper atmospheric density at the same altitude. The consequent change of atmospheric density directly influences orbiter’s running and the precision of prediction of orbit. On the other hand, change of atmospheric density resulted from sunlit and shaded area has something to do with different factors of solar-terrestrial physics, some discussion can be taken into about these related phenomena. Although data of American earlier balloon detection were already used to the discuss the day-change of upper atmospheric density, due to limit of ways and means, there are rare specifications of the change. And the later AE, DE satellite etc. all run at elliptical orbits, it is difficult to provide data for the discussion of the phenomena mensioned above. In this article, we applied the data from "SZ-2" Atmospheric Density Detector, which are the direct measurement results at a quasi-circle orbit and very helpful for the discussion of atmospheric density change in sunlit and shaded area.In this paper, the data on thermosphere density collected by "SZ-2" Atmospheric Density Detector from February to April, 2001 are used to search the change of the thermosphere density in the sunlit and shaded area during solar and geomagnetic active period. The results show that in the sunlit area, the peak value of atmospheric density changes as F_10.7 varies; during geomagnetic active periods, the peak value of atmospheric density at shaded area increases as Ap increases, and starts first at higher latitudes, then gradually move to lower latitudes.