大气顶射出长波辐射（OLR）是大气顶辐射能量平衡的重要分量。风云三号D星和E星（FY-3D和FY-3E）上搭载的中分辨率成像光谱仪（MERSI）均可用于OLR反演。利用美国Aqua CERES OLR瞬时观测数据分别对FY-3D和FY-3E MERSI瞬时OLR反演精度进行一致性比对，结果显示两颗星OLR反演精度基本一致，FY-3D和FY-3E MERSI OLR与Aqua CERES OLR相比RMSE在6-7 W·m-2之间。基于CERES日平均OLR数据与FY-3D和FY-3E单星和联合计算的日平均OLR比对结果显示，基于两颗卫星每日四次观测计算的日平均OLR较单颗星每日两次计算的日平均OLR精度提高3-4 W·m-2。反映出利用多颗极轨气象卫星观测数据，增加每日观测次数，可更好地反映OLR日变化特征。

Outgoing longwave radiation (OLR) of the atmosphere top (TOA) is an important component of the radiation energy balance. The Fengyun-3D (FY-3D) and Fengyun-3E (FY-3E) polar-orbiting meteorological satellites, launched in November 2017 and July 2021 respectively, carry the Medium Resolution Spectral Imager (MERSI) II and Low Light (LL) instruments. Both instruments have the capability to retrieve outgoing longwave radiation (OLR) using two water vapor channels and two window channels. In this paper, based on the introduction of the MERSI OLR inversion algorithm of Fengyun satellite, the instantaneous OLR retrieval accuracy of FY-3D and FY-3E MERSI is compared by using the instantaneous observation data of Aqua CERES OLR. The comparison results show that the instantaneous OLR retrieval accuracy of FY-3D and FY-3E is basically the same as the instantaneous OLR data of Aqua CERES. The RMSE of FY-3D and FY-3E MERSI OLR is between 6-7 W?m-2 compared with that of Aqua CERES OLR. It reflects that although there are differences between the performance of the MERSI instruments of the FY-3D and FY-3E satellites, the OLR retrieval capabilities of the two satellites are comparable. The comparison results of the daily average OLR data based on CERES between the single and joint calculations of FY-3D and FY-3E show that the daily average OLR calculated based on the four times of the two satellites per day is 3-4 W?m-2 higher than that calculated twice a day for a single satellite. The global daily average OLR data for the 7 months from June to December 2022 were selected as an example. Compared with the daily average OLR of CERES, the daily average OLR obtained by FY-3 two satellites is significantly improved compared with the root mean square error of the daily average OLR calculated by a single satellite. It shows that the daily observation data of multiple polar-orbiting meteorological satellites can better reflect the diurnal variation characteristics of OLR. The comparison process involves the spatio-temporal matching of data, reprojection and resampling schemes will affect the validation results. Compared with CERES, the difference between the retrieval OLR of the low-temperature target is higher than that of the high-temperature target regardless of the daily average OLR calculated based on the single or double satellites of Fengyun-3. The reasons for this are multifaceted and need to be further analyzed. The research results show that the joint application of multiple polar-orbiting satellites with a certain instantaneous observation interval can effectively improve the calculation accuracy of the daily average OLR in the cloud area. But how to construct the daily variation model of OLR and deepen the calculation method of the daily average OLR needs to be further studied.