Abstract: An inflatable flood barrier includes a board having a side plate and a peripheral plate attached to the side plate. The board being provided with a charging port, the peripheral plate has rounded corners, and the side plate has corner portions. The rounded corners and the corner portions are positionally corresponding. The corner portion has guiding grooves. A flexible seal embraces at least a part of the peripheral plate and has an internal channel, a gas inlet and a gas discharging port. When the flexible seal is inflated at the internal channel, a watertight combination between the inflatable flood barrier and a contacting surface of a gate it protects is achieved. The inflatable flood barrier is structurally simple, watertight, convenient to use and store, apparently pleasing, and functionally versatile.