Abstract: The Dagangshan arch dam was strongly shaken when the Luding 6.8 magnitude earthquake and its aftershocks occurred on 5 September 2022. In order to study the internal damage and post-earthquake safety stability of the Dagangshan arch dam under the action of this earthquake, the microseismic monitoring system of the Dagangshan arch dam was used to effectively monitor the microfracture phenomenon of the arch dam under the action of the earthquake for the first time. On this basis, the evolution process and causes of dam microseismic events under the influence of the earthquake were explored, the risk area of the Dagangshan arch dam under the action of earthquakes was proposed, and the safety and stability of the arch dam were evaluated after the earthquake. The results show that the surge of microseismic events at the Dagangshan arch dam is closely associated with seismic distur￣bances. Microseismic activity in the arch dam is weak before the earthquake, and the number of microseismic events is low. During and after the earthquake, stronger external seismic disturbances cause continuous displacement and deformation of the arch dam, resulting in stress adjustments in the dam body, which induces a large number of microseismic events, and the maximum number of microseismic events in a single day is as high as 231. The spatial distribution of microseismic events and the main impact areas of microseismic deformation reveal that the risk areas of the arch dam are the middle and upper areas of dam sections 5^#~6^#, 10^#~11^#, 13^#~16^#, and 19^#~20^#, centered on the dam section where the crown cantilever is located. In a period of time after the earthquake, the number of microseismic events in the dam decreases gradually, and the microseismic apparent volume and energy release of microseismic events are able to return to the pre-earthquake level. The microseismic events of the dam do not expand to form obvious macroscopic cracks, and no damage is found in the dam; the Dagangshan arch dam is still safe and stable after the earthquake disturbance.