Slope deformation and landslide are one of the most common and serious geological hazards in Mines worldwide. The spatiotemporal characterisitics of a deformed slope are crucial for studying landslide mechanisms and assessing potential risks. Using the Libi slope in Shanxi as an example, this study quantitatively investigated the spatiotemporal deformation characteristics in its evolution process using two strain models based on small and finite deformation conditions. The results show that strain analysis is an effective method to quantitatively study the spatiotemporal heterogeneous characteristics of a deformed slope and its retaining wall. Local strain extrema are closely related to crack activity in a deformed structure. The concentration of local strain extrema characterizes the crack activity on the wall and slope. Especially the latter one, the surface expansion strain extrema exhibited multi-transitions of opposite deformation characteristics and the extrema of maximum shear strain rates had exceeded 40 μstrain on the slope and 200 μstrain on the retaining wall before the landslide happened. In summary, strain analysis of slope deformation has benefits to provide rich details for the study of slope deformation evolution mechanisms, which could be an essential support for risk assessment and hazard warnings.