Abstract: On May 2, 2021, a lightning accident occurred in Haha Township, Mianning County. Based on field investigations, local climatic conditions, weather conditions, meteorological data, and data from Sichuan Lightning Early Warning and Monitoring Network, the causes of the lightning accident are analyzed comprehensively. The results show that: The average annual number of thunderstorm days in Liangshan Prefecture is about 55.7 days, and the four counties of Yanyuan, Mianning, Yuexi and Muli are the hardest-hit area of thunderstorms. July and August are the months with the most thunderstorms, followed by April, May and October, and the number of thunderstorm days in other months is less. This lightning strike event was caused by the formation of multiple strong echo centers under the action of warm and humid airflow in the middle and lower layers, and the thunderstorm cloud with strong development of oblique rise was very conducive to the generation of frequent lightning.