The invention discloses a functional ecological floating bed water purification device. The device mainly comprises a floating bed arranged at the upper layer, and a functional ecological area arranged at the lower layer, wherein aquatic plants are planted on the floating bed, functional filler with a high specific surface area is hung at the lower layer, and a sustained-release material with an oxygen release function is placed in the middle of a filler area; the device provides a dissolved oxygen for a system, so that the stench, produced by the lack of oxygen, of the water can be reduced. Due to the different concentration distribution of the dissolved oxygen, the lower functional ecological area is divided into an anaerobic zone, an anoxic zone and an aerobic zone; therefore, the distribution of biological population is enriched, pollutants in degraded polluted water can be effectively removed, the nitrogen and phosphorus removal effect is improved, and the water environment is effectively improved and repaired. In addition, by means of reasonable collocation of the multiple ornamental aquatic plants having stronger synergistic decontamination ability on the floating bed, the purification of water is promoted, the visual environment of the water is improved, and the living standard is raised.