Abstract: This paper examines a large scale toppling rock slope on upper reach of the Yellow River. It is alternatively composed of countertendency bedded sandstone and thinly bedded slate. There are mainly tension cracks in the sandstone and flexural deformation in the slate. As a result of the combination of the two different time-dependent deformations, the evolution of the whole toppling rock slope is characterized as long-term, slow and progressive. Based on the combination mode of rock masses and the form of the deformation and failure, the space distribution features of the time-dependent deformation in the sandstone and slate are presented. The temporal and spatial evolution character is summarized. The mechanism of the evolution is researched. The influence of the combination mode and the structure of the rock masses as well as unloading fissure and landform during the evolution of the toppling rock slope are discussed.