Abstract: To study the mechanical property degradation of the heat-shrinkable sleeve in satellites under charged particles environment in GEO space, tests are carried out with respect to the degradation of the elongation rate at break and the tensile strength of the heat-shrinkable sleeve by high energy electron of 1 MeV and low energy electron of 45 keV. It is shown that there is a significant degradation of the mechanical properties under the irradiations, especially, of the high energy electron. The energy deposition, the radiation-induced gases, the surface morphology, and the XPS diagram are analyzed. The research provides some guidance for choosing appropriate energy particles to effectively simulate the degradation of mechanical properties of bulk materials.