Multi-stage treatment device and treatment method for repairing polluted underground water

The invention discloses a multi-stage treatment device and a treatment method for polluted underground water remediation. The device comprises a fixed disc, a primary filter assembly, a flocculation purification assembly and a power assembly, wherein a well casing is arranged on the lower bottom surface of the fixed disc; the primary filter assembly is arranged on the fixed disc; the primary filtering assembly comprises a filtering box, a filtering net sleeve clamped in the filtering box and a limiting rod arranged in the filtering box, and a dirt scraping plate is arranged on one side of the limiting rod; the flocculation purification assembly comprises a flocculation box arranged outside the filter box in a sleeving manner, a vibration disc arranged in the flocculation box and a vibration component arranged in the flocculation box; the power assembly is used for providing power for the filter screen sleeve and the vibration component; the device is reasonable in structural design, remarkable in polluted und