Abstract: Glass fiber/epoxy composites have high insulation and high mechanical properties. They are usually employed as the supporting materials in high energy physics and nuclear physics tests. But the mechanical properties will vary in irradiation environments. As one kind of glass fiber/epoxy composites, glass-cloth/epoxy laminated sheet is employed according to the application requirements of new generation Beijing Electron and Positron Collider (BEPCII). The compression properties of glass-cloth/epoxy laminated sheet before and after γ irradiation were studied. The result shows that the compression strength of glass-cloth/epoxy laminated sheet reduces to 315.05 MPa from 320.21 MPa after the γ irradiation of 20 kGy, declining by 1.61%. The compression strength of glass-cloth/epoxy laminated sheet reduces to 312.30 MPa after the γ irradiation of 200 kGy, declining by 2.47%. The fracture sections of the samples before and after irradiation were observed by SEM.The results show the glass-cloth does not change obviously and the binding degree of the glass-cloth and the epoxy declines after irradiation. The fragmentation of epoxy is more obvious. FTIR spectra indicates that the degradation reaction predominates over the crosslinking reaction of epoxy after irradiation.