The engineering properties and stability of soil-like slope obviously differ from those of homogeneous soil slope and rock slope. In actual construction projects, soil-like slopes are regarded as general homogeneous soil slope and rock slope, resulting in inadequate reliability, or conservative support. Research on the geomechanical model and instability mechanism of soil-like slope is of practical significance. In this paper, Dongtangwan slope in Hechuan district of Chongqing is taken as a geological prototype to analyze the geological conditions, structural features, and deformation behaviors of the slope. Results reveal that the geomechanical model is progressive backwards creep slide-tension fracture; instability analysis shows that the failure of soil-like slope usually happens in storm or continuous rainfall, with some lag in time, and the instability is mainly controlled by the gently-inclined structural planes and steep-inclined fissure planes. Furthermore, the slope stability is analyzed and evaluated based on plane sliding mode. The calculation results are consistent with the deformation characteristics of the slope.