The invention relates to the technical field of environmental greening, and particularly discloses a water purification system based on an ecological landscape on a freshwater mud flat. The water purification system comprises a retaining wall with one surface close to a lake, and a wetland structure connected to the other surface of the retaining wall, wherein water passing holes for communicatingthe lake with the wetland structure are formed in the retaining wall; the wetland structure is communicated with a forest water supply purification structure and a farmland water changing structure;the forest water supply purification structure comprises a soil layer and a water conveying layer located below the soil layer; the water conveying layer is bent into a wave shape along the vertical direction; the water conveying layer is provided with a first isolation layer a first detritus layer, a first gravel layer, a first filler layer and a first flow guide layer in sequence from bottom totop; the first detritus layer is provided with a water feeding end communicated with the wetland structure and a water discharging end communicated with the farmland water changing structure. According to the water purification system based on the ecological landscape on the freshwater mud flat, by the additional arrangement of the water supply purification structure and the farmland water changing structure, the greening area can be enlarged, the water purification effect is enhanced, and the advantages of the mud flat are fully used; manual irrigation for trees is not needed, so that the labor intensity of a worker is relieved, and the yield of crops is increased.