In order to illustrate geomorphic characteristics in different sorts of formations, 10 small watersheds from Ar-Pt, C-O, C-P, T, and Q formations in the foot of Lyuliang Mountains were selected as the research objectives and the relationship between the area of these watersheds and its vertical gradient, as well as the geomorphic parameters including the width of the rivers, branch ratio, and curvature, were obtained by using ArcGIS software. We got such conclusions: (1) In 20 km2 research area, the erosion resistance of these formations is Archean Proterozoic > Triassic > Carboniferous Permian>Cambrian Ordovician>Neogene Quaternary loess and its resistance coefficient is 2.294, 2.232, 1.486, 1.394, and 1, respectively, if the formation time, paleoenvironment, and structural development do not show a clear difference. (2) The longer the river formation time is, the smaller the branch ratio of the river system is; The shorter the river formation time is, the larger the average width between tributaries is; The longer the river formation time is, the smaller the vertical gradient is, and the development trend is towards equalization.