This paper designs a large aperture in tegrating sphere radiometric source system.The laboratory radiometric calibratio n is an important part during the development of the space optical remote sensor and its effect is to build the response function between input radiance and out put electric signal.This process usually uses an integrting sphere as the radiom etric source.The principle of radiometric calibration follows full aperture,full field of view and end to end.The extended radiometric source is the standard so urce of laboratory radiometric calibration and is required to illuminate the cam era with full aperture and full field of view,so it must have large hatch diamet er and ideal cosine radiation performance.At present,the radiometric calibration device needs a large-scale integrating sphere.Systematically,this paper descri bes the design method and process of a large aperture integrating sphere.We tes t the radiation characteristics of the large aperture integrating sphere,including the uniformity,the stability,the cosine characteristics and the output uncertai nty.The diameter of the integrating sphere is 3000mm and the opening diameter is 1000mm.The test results indicate that t he output uncertainty of this system is 5%.