The invention discloses a flood prevention device which is formed by splicing and combining a plurality of independent flood prevention units. Each flood prevention unit comprises a bottom plate, a support frame, a steel plate, an energy absorption sponge, buffer baffles and buffer stop strips, wherein the energy absorption sponge is paved on the steel plate, the buffer baffles are arranged on theinclined face, opposite to the bottom plate, of the steel plate at an interval, and the buffer stop strips are arranged on the horizontal plane opposite to the bottom plate; and the baffle stop strips are flexible, and each buffer stop strip comprises two carbon fiber meshes, two sponge strips and a plurality of sponge particles. The flood prevention device can effectively reduce the impact forceof water flow; the energy absorption sponges can further reduce the impact force, and especially after a previous flood peak wets the energy absorption sponges and when flood peak water flow coming again meets with the wetted energy absorption sponges, the impact force can be obviously reduced; besides, the weight of the energy absorption sponges is greatly increased, the water resistance of theflood prevention device is higher, and the bottom plates are not easy to move when the downward pressure borne by the bottom plates is increased; and during installation, the weight of the energy absorption sponges is low when water is not absorbed, and the flood prevention device is convenient to carry.