The invention relates to a rescuing and flood-discharging method and specifically relates to a method for channeling and discharging a barrier lake, wherein the barrier lake adjacent to the barrier lake surface is provided with a working platform which can be exposed out of the water surface and bear large-scale equipment, the working platform is provided with a high-lift pump with high water yield and a power supply unit, one end of the pump is connected with a dewatering pipeline which is arranged below water; the other end of the pump is connected with a drainage pipeline, the outlet end of the drainage pipeline aligns at the lower end of the barrier body; water can be extracted from the lake through the pump and constantly impacted to the lower end of the barrier through the drainage pipeline and the barrier is formed into a drainage galley by water flow impact force, thus the device is low in cost, excellent in security and high in operability.