The invention discloses an artificial floating bed system for purifying water quality by using superfine fibers. The artificial floating bed system comprises a floating bed, a planting basket, planting basket filler, floating bed plants, superfine fiber three-dimensional artificial waterweeds, a supporting frame, an aeration device, a microbial preparation and a box body. The invention also discloses a method for purifying water by using the system. The method comprises the following steps of: aerating and oxygenating sewage through micropores, and intercepting, adsorbing and decomposing pollutants in the sewage by a biological membrane attached to the superfine fiber three-dimensional artificial waterweeds in the superfine fiber artificial waterweed restoration area. Pollutants in the water body are absorbed, metabolized and decomposed by microorganisms at the roots of the plants and on the attached filler when flowing through the plant synergistic microorganism remediation area. A microbial agent is added, and microorganisms are used for effectively adsorbing, converting and degrading nitrogen and phosphorus in the water body, so that algae propagation is inhibited, and the waterbody is effectively purified. The artificial floating bed system has the advantages of readily available materials, low construction and operation costs, convenient manufacture, landscape beautification, water quality improvement, and good application prospect.