At about 04:00 on 10 August 2019, the heavy rainfall carried by Typhoon Lekima induced a catastrophic rockslide in Shanzao Village, Yongjia County, China. The heavy rainfall triggered the tuff rock mass of about 12×10⁴ m³ in volume sliding along the interbedded mudstone. Subsequently, the Shaozao river at the slope toe was blocked by the sliding mass, which formed a landslide dam afterwards. The dam broke later, ruining many houses and causing 32 casualties. We investigated the geological setting, characteristics, and failure mechanisms of the Shanzao rockslide through field investigation. In addition, the dynamic course of the landslide was analyzed using discrete element method. This paper reveals the dynamic course and risk assessment of the rockslides in the mountainous areas of the Southeast China. The findings can provide guidelines for processing the landslides with similar geological conditions.