The invention relates to a beneficiation method for lean ore containing soil-powder-shaped magnets, in particular to an on-site ore enrichment method for lean ore containing soil-powder-shaped magnets. The main purpose is to solve the problem that in the prior art, ore is difficult to recover from the lean ore containing the soil-powder-shaped magnets. A belt conveyor is arranged and connected with a screening machine, and the pore diameter of a screening plate of the screening machine is 3 mm-4 mm. A water storage tank is arranged, a water feeding pipe and a spraying water-feeding pipe are arranged on the water storage tank, the spraying water-feeding pipe is connected with a spraying pipe set, and the spraying pipe set is arranged above the screening machine. Oversize materials of the screening machine are connected with a feeding port of a dry magnetic separator, an ore pulp tank is arranged below the screening machine and connected with a feeding port of a wet magnetic separator, an ore discharging pipe of the wet magnetic separator is connected with a dewatering tank, and a water outlet of the dewatering tank is connected with the water storage tank through a leaching water return pipe. A tailing pulp discharging pipe of the wet magnetic separator is arranged above a high-frequency linear dewatering screen, a muddy water tank is arranged below the dewatering screen and connected with a water inlet of a box type thickener through a muddy water return pipe, a clear water outlet of the thickener is connected with the water storage tank through a clear water return pipe, and a slurry outlet of the thickener is throughout the upper portion of the high-frequency linear dewatering screen through a slurry pipe. The on-site ore enrichment method has the advantages that the recovery rate of iron ore in the lean ore containing the soil-powder-shaped magnets is increased; tailings are dewatered and discharged on the site in a dry mode; cycling use of water is achieved, and the rate of consuming new water is low.