For upland ephemeral gullies, gully erosion is strongly related to the formation and migration of cyclic steps. It is necessary to provide insight into the process of cyclic step development to accurately predict the pace of landscape evolution and soil loss. Information on the geometry of cyclic steps in subaerial environments is limited, and, to our knowledge, no model of cyclic step development considers plunge pool erosion. In this study, we analyze the geometric features and controlling factors of erosional cyclic steps through meta‐analysis of measured data including new measurements in the Loess Plateau, China. We focus on cyclic step dynamics of fluvial beds controlled by bed shear stress and local plunge pool erosion. We develop a new theory to incorporate plunge pool erosion through adapting existing cyclic step and plunge pool models. Our method agrees with measured data, showing that a larger flow rate leads to larger step length Ld and height Hd and increasing erodibility increases step aspect ratio Ld/Hd. The method is also able to predict how the step length, height, and aspect ratio change with the average channel slope. Our results indicate that plunge pool erosion is an important mechanism of cyclic step evolution. However, plunge pool development alone is not sufficient to explain the wide range of Ld/Hd in the measured data. The posed theory relates to equilibrium conditions and thus cannot consider temporal adjustments in step geometry. Plain Language Summary The beds of upland ephemeral gullies often have long profiles with a discontinuous series of upstream‐migrating steps. Channels with these steps show characteristics of water flow and sediment transport that differ from channels where steps are absent. This difference in turn affects the rates of landscape evolution and soil erosion. In the Loess Plateau, China, periodic steps are accompanied by plunge pool erosion below a free overfall. No models to date tie both step and plunge pool formation. In this study, we present geometric data of steps measured in a small watershed of the Loess Plateau. We develop a theory that models periodic steps with plunge pool erosion. We identify the factors that control step geometry through meta‐analysis of measured data and numerical modeling. The results show that discharge, bed erodibility, and slope are coupled with each other in the establishment of step‐pool geometry. Furthermore, we find that plunge pool erosion is a key mechanism that controls the trend between step height and slope. However, the new model fails to completely describe the wide range of values of step length divided by step height, probably because it does not consider the change in step geometry over time. Key Points Length and height of cyclic steps increase with flow rate in measured data and model predictions Smaller channel slope and larger bed erodibility result in a larger step aspect ratio in measured data and model predictions Adding plunge pool erosion improves model predictions for step length, height, and aspect ratio relative to the average channel slope