To control the production cost of the particle electrodes, a novel particle electrode was prepared using the steel slag, which has certain magnetism and could be applied for the dyeing wastewater treatment. The steel slag particle electrodes, with a saturation magnetic induction of 1.638 6 A·m²/kg, were characterized by SEM and VSM. Moreover, the prepared magnetic particle electrodes were utilized in a three-dimensional electrochemical oxidation system for simulative printing/dyeing wastewater treatment. Experimental results showed that the optimal parameters were: initial concentration of the solution of 5 mg/L, initial pH value of 4, applied voltage of 5 V, and concentration of the supporting electrolyte of 0.15 mol/L.