Polysiloxane composite coating was coated on the surface of Q235 steel through sparying method,and the samples were corroded by atmospheric exposure test in four 220 kV transformer substations (heavy pollution area,densely populated area,general industrial area,rural settlements area) for 15 months respectively.The corrosion behavior was investigated by Tafel polarization curve and electrochemical impedance spectroscopy (EIS) test.The results show that the corrosion current density increases from 3.849 5×10^-12 A/cm² to 2.257 2×10^-10 A/cm² with the extension of time in the densely populated area.The corrosion current density decreases from 1.640 1×10^-10 A/cm² to 5.736 5×10^-11 A/cm²,and then increases to 3.929 9×10^-10 A/cm² in the densely populated area which shows the best anticorrosion ability.Combined with the self corrosion potential and coating resistance,the order of anticorrosion ability in different environment is as follow:densely populated area > rural settlements area > general industrial area > heavy pollution area.