Fe₃O₄ microsphere is a good candidate as support for catalyst because of its unique magnetic property and large surface area. Coating Fe₃O₄ microspheres with other materials can protect them from being dissolved in acid solution or add functional groups on their surface to adsorb catalyst. In this paper, a carbon layer was coated onto Fe₃O₄ microspheres by hydrothermal treatment using polyethylene glycol as the connecting agents between glucose and Fe₃O₄ spheres. Through tuning the added amounts of reactants, the thickness of the carbon layer could be well-controlled. Because of the abundant reductive groups on the surface of carbon layer, noble metal ions could be easily adsorbed and in situ reduced to nanoparticles (6-12 nm). The prepared catalyst not only had unique antiacid and magnetic properties, but also exhibited a higher catalytic activity toward the reduction of methyl orange than commercially used Pd/C catalyst.