Sapphire single crystal for optical window material was irradiated by rays and particles when served in the space environment, thus, the optical properties and structure would be changed even the window lost its effectiveness. The change of the surface roughness and transmittance caused by electron, proton and integrated currents was discussed through the ground simulation experiment. The AFM test indicated that the space particle irradiation led to roughness decreased with dose effect and energy effect, meanwhile, the integrated current caused the maximum effect and the electron minimum; different range between electron and proton caused the distinguishing effect on roughness of back side. According to the UV-Vis-VIR and FTIR testing result, the particle irradiation gave rise to decrease of transmittance accompanied by dose effect and energy effect, especially in ultraviolet band, different kinds of particle caused different effect in each band.