Abstract: On July 23, 2019, a catastrophic landslide occurred in Jichang Town, Shuicheng District, Liupanshui City, Guizhou Province, resulting in the tragic loss of 43 lives, with 9 people still missing, and causing direct economic losses estimated at approximately 103 million Yuan. Following the landslide, significant debris and an unstable slope continued to threaten the nearby residences in the Pingzhai and Pingxing groups. Through comprehensive on-site investigations, this study identifies and analyzes both the geological environment and contributing factors of the Shuicheng landslide, providing an in-depth understanding of its triggering mechanisms. For the first time, a thorough stability analysis of the post-landslide residual deposits and the adjacent unstable slope under varying precipitation conditions is presented. The results indicate that extreme rainfall may trigger secondary landslide within the extensive debris deposits from the Shuicheng landslide. Additionally, we performed a dynamic behavior analysis of the unstable slope using rheological models and depth-averaged approaches. The findings provide essential insights into the dynamical mechanisms driving secondary landslide disasters and are crutial for safeguarding the lives and properties of residents at the slope toe.