T2 copper was immersed in ethanol and diesel respectively and the characteristics were investigated including the corrosion morphology, precipitate composition, corrosion rate and solution color. The corrosion behavior of ethanol on copper metal parts in fuel system was studied according to the dynamic potential polarization curve. The results show that the changing rates of above-mentioned parameters from the specimen are consistent with those of the potential and current density of self-corrosion. The corrosion of T2 in ethanol is more serious than that in diesel because oxygen element of ethanol is easy to react with T2 to form metal oxide, which accelerates the corrosion by further reacting with hydroxyl in ethanol to form acetic acid.