The invention belongs to the technical field of environmental protection and relates to a method for purifying water in rivers or slowly flowing water. In the method which is a technical method for improving water quality, pollutants in the water are absorbed by the plant root system and adsorbed by a matrix and purified by using the rhizospheric microorganisms living in the matrix; and an impeller is driven to rotate by wind energy so as to enhance the water power and increase oxygen content in the water. The method realizes multi-layer removal of water pollutants through the absorption and purification by the plant root layer, adsorption and purification by the matrix layer, oxygen increase in water and the like and accelerates the ecological restoration process of the water by organically combining the plant restoration technology and the physical restoration technology.