Integrating spheres play a central role in the radiometric calibration of remote sensors. With thedevelopment of the wide field of view (FOV) remote sensors, aperture diameters of remote sensors arebecoming larger and larger. To satisfy the radiometric calibration requirements of full FOV and fullaperture, an 8000mm diameter large aperture integrating sphere uniform source with a variable exit portwas designed and manufactured. This integrating sphere will be used for pre-launch test and radiometriccalibration of remote satellites. In this paper, optical theories were used to design the output spectralradiance. The LightTools software based on ray-tracing simulation method was used to determine the bestcombination and distribution of inner light sources. A spectral experiment was made to verify the spectralradiance design. To reduce the influence of longtime power-on, a new characteristic measurement methodwas developed to obtain the radiation characteristic of the integrating sphere, which could greatly improvethe measuring efficiency. This method could also be applied to measure other large aperture uniformsources. The obtained results indicate that the spatial uniformity is 98.35%, and the angular uniformityat center position is 98.78%.