The work aims to obtain magnetic Fe3O4/active carbon with better adsorption capacity, magnetic separation property and regeneration performance. The magnetic Fe3O4/active carbon was prepared by chemical co-precipitation method, and were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The magnetic Fe3O4/active carbon was used to adsorb Cr(VI) in electroplating waste water, and the effects of adsorbent dosage, pH and adsorption time on adsorption property were investigated, and the corresponding adsorption kinetics was researched. Then magnet was used to reclaim the magnetic Fe3O4/active carbon. The magnetic Fe3O4 active carbon contained high purity cubic phase magnetic Fe3O4 particles. The adsorption rate could reach 97.44% under the optimal conditions of dosage 0.15 g, pH=3 and absorption time 120 min at 25 ℃. The absorption kinetics could be described by pseudo-second-order kinetics model. The co-existing cations could enhance the adsorption capacity, but the co-existing anion might reduce adsorption capacity. The recovery rate of magnetic Fe3O4/active carbon was 93.58% using magnet. Adsorption amount of Cr(VI) was 27.17 mg/L after six successive adsorption-regeneration cycles. the removal rate of Cr(VI) in electroplating waste water is better using magnetic Fe3O4/active carbon as adsorbent. The recovery method is simple and the recovery rate is high, so the adsorbent has a good application prospect.