The invention discloses a surface coating for a heat exchanger. The coating comprises a priming paint layer and a Teflon layer from inside to outside, wherein the priming paint layer is 7-9 mum in thickness; the Teflon layer is 20-30mum in thickness. Moreover, the invention further discloses a surface treatment method for the heat exchanger. The method comprises the following steps: drying and degreasing the surface of the heat exchanger, removing oil impurities on the surface, and removing a surface paint layer or oxide impurities by performing sand blasting or rinsing; spraying a priming paint layer or a Teflon layer, and soaking a layer of grease outside a Teflon coating, wherein an aluminum base surface is tightly bonded with the Teflon layer through the priming paint layer, and Teflon has hydrophobic and oleophylic characteristics, so that a selected oil layer can be adsorbed onto the surface tightly. The coating surface has the characteristics of mist resistance and frosting delay of a hydrophobic surface as well as the characteristic of easiness in defrosting and draining of an oil layer.