Water body purifier

The invention provides a water body purifier. The water body purifier comprises a box body and a separation plate, wherein the separation plate is used for separating the box body into a water storage cavity and a purification cavity; a water outlet is formed in the bottom of the water storage cavity; and a water inlet is formed in the bottom of the purification cavity. The water body purifier is characterized in that a reverse osmosis membrane is arranged at the upper part of the separation plate; the purification cavity is internally provided with a pipeline, an active layer and a filtering layer; one end of the pipeline is over against the reverse osmosis membrane; the active layer and the filtering layer are arranged below the pipeline in sequence; and the pipeline is internally provided with a sterilization lamp. The purification cavity is internally provided with the filtering layer and the active layer in sequence so that solid pollutants suspended in a water body and most of harmful substances and microorganisms can be filtered and the sterilization lamp is used for removing harmful microorganisms and pathogenic bacteria in the water body; on one hand, the water body is purified; on the other hand, the service life of the reverse osmosis membrane is prolonged; and dissolved salts, colloids, microorganisms, organic matters and the like in the water are removed by the reverse osmosis membrane so that a purification effect of the water body is very good.