Abstract:The MS6.4 earthquake occurred at 21:48 PM on May 21,2021,in Yangbi County,Dali Prefecture,Yunnan Province. China Earthquake Networks Center reported the formal quick report in 8min. After the earthquake,together with some units of China Earthquake Administration,China Earthquake Network Center immediately started work on the emergency output of earthquake-related products,producing a total of 9 categories and 14 data products including basic seismic parameters,historical earthquakes,seismological tectonics,source mechanism,instrumental seismic intensity and aftershocks precision positioning,and so on. These products implies that this earthquake occurred at the western part of the Yunnan,Chuandian block,located near the Weixi-Qiaohou-Weishan faults. Focal mechanism result suggests a strike-slip event,the fault heading north-west to south-to-east. The aftershock mainly expands about 20km along the southeast direction of the main earthquake. The depth mainly concentrates in 10km and in a shallow range. The predicted intensity of the epicenter area reaches eight degree. The area involves Taiping Township,Fuheng Township,Yangjiang Town and Cangshan West Town,with an area of about 227 square kilometers. The three-component peak acceleration values recorded at 9km from the epicenter are greater than the fortification standard in the area. It implies that the earthquake could cause casualties and house damage in Yangbi County near the epicenter,which was consistent with the disaster investigation on site.