The estimation and correction of long-term radiometric degradation in remote sensing instruments are crucial for improving the stability and accuracy of satellite remote sensing applications. This study used long-term observation data of FY-3D/MERSI-Ⅱ over stable targets in deserts and DCC (Deep Convective Clouds) to establish a function relationship model between instrument radiation response and time. We further obtained estimates of the best radiometric response degradation and radiometric calibration coefficient using the inverse variance weighted average method to integrate the results of two stable targets. The radiometric degradation tracking resultsshow that from the beginning of FY-3D/MERSI-Ⅱs in-orbit to September 2022, there is significant degradation in three blue light bands (band 1, bands 8—9 with wavelengths less than 500 nm) and four near-infrared-shortwave infrared bands (bands 5—7, band 19 with wavelengths greater than 1 000 nm), with annual degradation rates ranging from 1.47% to 4.32%. Precision testing of L1 products reveals that the operational calibration bias of seven significantly degraded Bands exceeded ±5%, with bands 5 and 8 having the most significant bias, about -20%. After applying the radiometric calibration coefficient sequence obtained in this study, the radiometric calibration precision remains stable over time, with calibration bias maintained within ±3%. The accuracy validation results of L2 products show that the use of newly obtained calibration coefficients has improved product accuracy compared to operational products. These results indicate the effectiveness of the radiometric calibration method established in this study.