Based on double solar diffusers on-board calibration system, a bidirectional reflectance distribution function (BRDF) attenuation monitoring model of calibration diffuser is established, and the structure design of solar attenuation screen for attenuating the incident sunlight flux is introduced. The attenuation screen transmittance is one of the key parameters that affect on-board calibration accuracy, and it need to be measured accurately before launch. It is measured repeatedly with the attenuation screen transmittance measurement system. Results show that the attenuation screen transmittance is 13.8% within the test angle range, and the test uncertainty is better than 0.54% (K is 2), which satisfies the requirements of on-board calibration. Test results can be used to establish the ground database, and it can provide data support for the later satellite calibration, which is of great significance to ensure the long-term on-board calibration accuracy.