Abstract: Magnetic CoFe₂O₄ submicrospheres were prepared by solvothermal method, and dopamine (DA) was polymerized on the surface under alkaline conditions with CoFe₂O₄ as the core. The polyhydroxyl reducibility of ethylene glycol and polydopamine (PDA) was used to reduce the Pt in situ on the surface of CoFe₂O₄@PDA to synthesize nano CoFe₂O₄@PDA@Pt composite. The micro morphology, structure and crystal morphology of the CoFe₂O₄@PDA@Pt composites were characterized by TEM, XRD, vibration sample magnetometer (VSM) and XPS. The catalytic activity of inorganic dye potassium ferrocyanate and organic dye p-nitrophenol were investigated as the target pollutants. The results show that the degradation rate of potassium ferrocyanate is over 95% and the degradation rate of p-nitrophenol is about 99.3% within 2 minutes.