Abstract: The geological environment in Yellow River delta is characterized by unusual hydrologic conditions, fine sediments, semi-arid climate and frequent flow-abruption. Consequently, many peculiar geological phenonena, such as the unusual erosion channels, are developed abundantly in the overwater plain. It is believed that these channels are formed by runoff resulting from rain and/or melt snow and ice under exposure condition. Based on their plane morphologies, the unusual erosion channels may be divided into six types, i.e., linear, dendritic, pit-like or hole-like, planar, net-like and tunnel-like channels. The size of channel is variable. The small channels usually are tens of centimeters in length and a few centimeters in width and depth, while the large one could reach up to tens of meters in length. The channel wall often has slump (deformation) structures, rill marks and silt stalatite-like structures.