Fine-mode aerosol optical depth is a key parameter required for atmospheric environment monitoring and climate change assessment.Directional Polarimetric Camera（DPC） onboard the Terrestrial Ecosystem Carbon Inventory Satellite（CM-1）launched in August 2022 was systematically introduced.A major improvement of DPC/CM-1 over other DPC sensors is that the nadir spatial resolution increased from 3.3km to 2.4km.According to the sensor and data characteristics of DPC/CM-1，a cloud detection method based on polarimetric and spectral/spatial texture characteristics was developed，and the multi-angle observation was coupled to achieve strict cloud pixel identification.The results of DPC/CM-1 cloud detection show that this method has good detection effect for bright surface such as desert areas，dark surface such as vegetation and hill areas，and the sun-glint and non-sun-glint areas over ocean.An improved fine-mode aerosol optical depth（FAOD）retrieval algorithm was developed.The FAOD retrievals were verified by the data of Aerosol Robotic Network.The validation results show that the slope of the fitted line reaches more than 0.95，and nearly 73% of the observed data are distributed within the expected error，indicating the reliability of the retrieval algorithm.The retrieval results of FAOD clearly show the spatial distribution characteristics of global FAOD.The high FAOD regions（reaching 0.7 to 0.9）mainly include India and Central Africa，where the high fine particle aerosol contents are probably due to the dense population distribution，strong industrial/agricultural emissions and biomass combustion.The preliminary retrieval results of DPC/CM1 during the in-orbit test phase show its potential for atmospheric environment monitoring and pollution transport analysis，especially when combined with its high spatial resolution，providing fine-scale atmospheric parameter retrieval results.
