Abstract: Rainfall landslides frequently occurred in the mountainous regions of Southern Anhui, posing a serious threat to human life and property. The authors took Yangjiawu slope in Zhuang Village of Jialu Town in Ningguo City as study case of typical rainfall slope in Southern Anhui. The dense distributed optical fiber monitoring and three-dimensional numerical simulation were integrated to analyze the spatial distribution characteristics of slope deformation and potential instability mechanisms combined with distributed optical fiber monitoring data. Field monitoring indicated that the overall deformation of the slope was minor, with no continuous, interconnected zone of concentrated deformation forming. Localized deformation was primarily distributed along the slope shoulder, the steep upper-middle sections, and existing defect zones. No stable linear relationship was observed between short-duration rainfall and the average absolute deformation. Strength reduction analysis indicated that as soil strength decreased, the plastic zone within the overlying gravelly soil gradually expanded from localized areas to the shallow, band-like region. Meanwhile, it tended to extend along the slope and the underlying weakly weathered fissured limestone exerted a certain constraining effect on the shallow slippage. Field monitoring and numerical simulations generally corresponded in terms of major deformation locations and evolution trends, indicating that potential instability in this slope was primarily characterized by shallow and localized slippage. The results could provide references for stability assessment, identification of critical areas, and monitoring and early warning systems for similar slopes.