In this paper,magnetic Fe3O4 nanospheres,prepared by a solvothermal method,and H2O2 were used to build a Fenton-like system to remove a typical cationic dyes,rhodamine B(RhB),in dyeing wastewater.The products were characterized by X-ray diffraction(XRD)and scanning electron microscopy(SEM).And the effects on the removal efficiency of RhB were discussed under various reaction conditions including H2O2 dosage,nanoparticles dosage,temperature,the pH value,and initial concentration of Rhodamine B.The experimental results show:20 mg/L RhB was removed 90% in 30 min and was almost removed in 60 min when H2O2 dose was 140 mmol/L,magnetic Fe3O4 nanoparticles dose was 1.2 g/L,at 30 ℃ and pH 3.