Several effect factors on the radiometric calibration results of space ultraviolet remote sensing instruments in orbit were studied,for the diffuse reflection ratio of a diffuser was changed in space environment.A device to study vacuum ultraviolet radiation characteristics of diffuser by simulating space ultraviolet radiation environment was build up,and the vacuum ultraviolet radiation characteristics of Al+MgF₂ diffuser in space ultraviolet remote sensing instrument were researched.The experimental results show that vacuum ultraviolet radiation accelerates the degradation of diffuser reflection ratio at 160～300 nm;the degradation value increases with the increment of radiation time;the degradation varies linearly at 160～300 nm and the degradation rate differs with the wavelengths.Finally,Factors that might cause degradation of diffuse reflection ratio were analyzed primarily.