Abstract: Satellite data assimilation pre-processing plays a crucial role in bridging satellite data pre-processing and numerical weather prediction model assimilation. It involves integrating pre-processed satellite measurements, orbital splicing and sparsification of satellite data, the fusion of boundary condition parameters under satellite pixels, and the assimilation pre-processing quality control of satellite data by using a unified file format and in accordance with the requirements of the data assimilation system. In the variational assimilation of numerical forecasts, assimilation pre-processing filters effective information from satellite pre-processed measurements, supports the positive contribution of satellite data assimilation to numerical forecast operations, and is an important link in determining the efficiency, quality and effectiveness of assimilation of large quantities of satellite data. In response to the complex format of satellite data from multiple channels, CMA has developed a standard format of high time-sensitive satellite data splicing technology in the pre-processing of satellite data assimilation, which effectively reduces the negative impact of the time lag of whole-orbit satellite data on operational numerical prediction. In the assimilation pre-processing of Fengyun satellite data, the assimilation prequality control of multi-spectral data fusion is achieved by front-loading cloud and precipitation detection, data analysis, analysis and other processing into the assimilation pre-processing, which ensures the positive assimilation contribution of Fengyun microwave temperature sounding data and infrared hyperspectral data. In the development of satellite data assimilation pre-processing technology, reprocessing of pre-processed satellite data by using a unified data format, expanding the processing for satellite imagery and active detection data, and front-loading a part of satellite data assimilation quality control function into data assimilation pre-processing are important trends in the development of future assimilation pre-processing technology for Fengyun satellite data.