Abstract: The centrifugal model tests on barrier dams overtopping are carried out based on the grain composition of Tangjiashan landslide dam, and the influence laws on the discharge process, released water and the size of the residual dam section of the drainage channel with trapezoid, triangle and compound forms are acquired. The characteristics of the flow in different parts of the channel during the discharge process are analyzed from the point of view of water dynamics. The results show that the compound section form has the characteristics of higher initial discharge efficiency, lower peak flow, higher residual dam and larger released water, in which the flow curve is "chunky-type". It can decrease effectively the pressure of flood protection caused by barrier dam discharge and reduce the water level greatly in a shorter time. It is an effective and safe method for the emergency handling of barrier dams.