Abstract: Tidal channels migrate frequently under the combined actions of coastal dynamics and bank collapse, significantly affecting the stability of tidal network systems. However, existing studies mainly focus on in-channel flow erosion during flood tides, while less efforts are devoted to bank retreat driven by seepage erosion during the ebb tides. It is thus urgent to understand the underlying mechanism of bank collapse that driven by seepage. This study investigates the impact of seepage head height on bank collapse through physical experiments, including bank collapse modes, bank line variations and bank retreat rate. Results show that the process of bank collapse is related to seepage head height. We observe a transition of bank collapse mode from cantilever failure to tension failure, with increased seepage head height. A positive correlation between bank retreat rate and seepage head height is found. Overall, this research reveals the mechanism of bank collapse driven by seepage, and explains the distinct failure process of bank collapse over ebb tides, which is of great significance to the study of tidal channel evolution.