Abstract: At present, the spectral radiation response function of the radiometer is calibrated by the irradiance standard lamp and diffuse reflector whiteboard, which cannot achieve linear calibration in a large dynamic range. A high-precision integral sphere light source with adjustable brightness was proposed. The output radiance was controlled by fixed and variable apertures, and the dynamic range reached 4 orders of magnitude. In addition,the spectral response function of the barrel-type radiometer was tested The experimental results show that the spectral response Function of barrel radiometer has good linear characteristics, high repeatability and the standard deviation of one-term coefficient is 2.78E-17.