Abstract: The purpose of this study is aims to investigate overflow breaching process of embankments constructed with silty clay and their as well as its response to flow and soil characteristics. Nine groups of experiments were conducted on the overflow breaching of cohesive embankments were conducted in a bend flume. Factors considered included inflow discharge, water content, and porosity of the embankment materials. Results showed: It has been found that the breach process can be categorized into a vertical erosion stage and lateral widening stage, with headcut retreat as the main form of erosion form during the vertical erosion stage. The soil water content and porosity not only affected the breach development rate, but also determined the final breach type. The inflow discharge, however, only affected has impact on the breach widening rate. The flow velocities and water level close to the breach were both restricted by the breach height. The relationship between the soil water content, soil porosity, and soil cohesion force was fitted using by the experiment data. A formula expressed by the soil cohesion force and flow parameters for computing the headcut retreat rate was proposed and was proved to be reasonable.