Abstract: It is known that, in magnetosphere substorm environment, there may occur very high absolute and differential charging on geosynchronous satellite, its insulating surface may be charged to very high negative potential, due to the energetic eiectron injection. For prediction of the spacecraft charging, it is important to measure the material charging properties. Usually, the 0-30 keV electron irradiation erivironment is used for simulating the substorm environment. This paper described the testing results on some of aluminized insulating films and ther mal control coating materials in 5 20keV electron irradiation conditions, and repoted the anomaly phenomena observed in measurement of surface potential at some of electron energy ranges.