Rill development causes considerable topsoil and nutrient losses, which affects agricultural production and environmental quality. Rill morphology formed by rill development has an important influence on runoff and hillslope erosion. This paper analyzed major achievements on rill developmental processes, rill morphological characteristics, and the relationship between rill development and its morphological characteristics. Furthermore, aiming for the major problems, the key fields, which need to be strengthened in studies of rill development and morphology, were proposed.