Abstract: The heterogeneous catalyst of magnetism is low cost, little hazardous, high efficient and easy separation from aqueous solutions. The Fe₃O₄/MnO₂ magnetic bimetal oxide catalyst prepared via hydrothermal method shows a better performance in activating 2KHSO₅·KHSO₄·K₂SO₄ for Rhodamine B (Rh B) degradation in aqueous solutions. Different quality of magnetic microspheres Fe₃O₄ and nanowire MnO₂ loaded together, synthesizing Fe₃O₄/MnO₂ catalyst with three different Fe₃O₄:MnO₂ mass ratios, which are 1:3, 2:3, 1:1. The characterizations of XRD, SEM and TEM show that two metallic oxide are loaded together. Compared with the catalytic performances of three Fe₃O₄/MnO₂ magnetic bimetal oxide catalysts according to activate 2KHSO₅·KHSO₄·K₂SO₄ for Rh B degradation in aqueous solutions, founding the Fe₃O₄/MnO₂(2:3) catalyst has the best catalytic activity. According to investigating the effects of reaction parameters on Rh B degradation on Fe₃O₄/MnO₂(2:3) catalyst, the best conditions of Rh B degradation in aqueous solutions are 10 mg/L Rh B, 0.4 g/L Fe₃O₄/MnO₂, 0.3 g/L 2KHSO₅·KHSO₄·K₂SO₄ and pH=8. After three cyclic utilizations, the 2:3 Fe₃O₄/MnO₂ magnetic bimetal oxide catalyst still have a good performance. SO₄^- plays an important role in degrading Rh B in aqueous solutions.