Abstract: The removal feasibility of 2,4-dichlorophenol (2,4-DCP) in groundwater by persulfate (PS) activated with ball-milling vanadium-titanium magnetite tailings (B-VTMT) was investigated. The morphology and composition of B-VTMT were analyzed by scanning electron microscope, X-ray diffraction, and X-ray photoelectron spectroscopy. The effects of B-VTMT dosages, initial PS concentrations, initial pH, initial 2,4-DCP concentrations, and common anions in groundwater (Cl^–, NO₃ ^–, and SO₄ ^2–) on 2,4-DCP removal efficiency were explored. The experiment results indicated that: The removal efficiency of 2,4-DCP was 45.4% within 39 h at room temperature under the conditions of B-VTMT dosage of 0.5 g/L, initial PS concentration of 5 mmol/L, initial 2,4-DCP concentration of 20 mg/L and initial pH 7.1. Radical quenching experiments and electron spin-resonance (ESR) spectroscopy confirmed that sulfate radical (SO₄ ^–·) and hydroxyl radical (·OH) were the main free radicals of 2,4-DCP removal. Eight intermediates were identified by high performance liquid chromatography-mass spectrometry (HPLC-MS). The possible degradation pathways of 2,4-DCP were speculated. The presence of chloride ions promoted the 2,4-DCP removal efficiency, while nitrate ions and sulfate ions inhibited the 2,4-DCP removal efficiency. It was concluded that B-VTMT could effectively activate PS to remove 2,4-DCP in groundwater, which was a promising way of tailings resource utilization.