To investigate the influence of the solar UV radiation on the absorptivity of the cavity of absolute radiometer of solar irradiance monitor on satellites,a simulated experiment is carried out in laboratory.A hydragyrum lamp with irradiance equaled to the total solar UV irradiance is used to irradiate the cavities.The change of the absorptivity of the cavity with the UV radiation quantum is measured by an integrating measurement instrument on the reflectance of black cavity within a full hemisphere(include the entrance of the Ulbrichtsphere),which can measure the absorbance of the mirror reflection and the diffused reflection in a high precision simultaneously.The results show that the UV radiation received by the solar irradiance monitor on FY-3 satellite will cause the absorptivity degradation of the cavity of absolute radiometers of 0.002% per year,and the most is 0.003% per year.The result is consistent with the changing instance of other absolute radiometers for measuring solar irradiance on other satellites basiclly.The experiment indicates that the UV irradiance has influence on the absorptivity of the cavity of absolute radiometer on satellites.The result also might supply essential reference for optimization,experiment,measurement and calibration of the solar irradiance monitor on satellites in future.