Abstract: This paper uses the encrypted automatic station rainfall, live observation data, FY-2G satellite TBB and NCEP/FNL 4 times daily 1 ° × 1 ° global reanalysis data to the central bell of Hunan on June 19, 2018. A detailed analysis of the causes of an extremely severe precipitation event at the topography. The results show that: (1) The extreme precipitation occurs in the background of stable and weak weather conditions; (2) The convective clouds of the same intensity under different terrains have significant differences in magnitude, and are extremely strong. The short-term heavy precipitation appears near the flared terrain or on the windward slope. (3) The infiltration of low-level shallow easterly winds and the blocking and forced uplift of small- and medium-scale terrain are the main reasons for the unusually strong ascending motion in extremely heavy precipitation areas; (4) The mid-easterly easterly wind carries dry and cold air into the ground and develops vigorously. The warming down tank is the main trigger mechanism for the occurrence of this strong convective weather. The long-term maintenance of the shallow Dongfeng airflow on the ground, the strengthening of the southerly airflow on the south side and the blocking effect of the terrain are beneficial to the long-term maintenance of the mesoscale shear line at the top of the terrain, which is the main reason for the persistence of heavy precipitation.