Abstract: Water-in-oil emulsion or water-in-oil emulsion with different water content were prepared with crude oil and produced water from an oil field. The corrosion behavior of 20 steel was studied by weight loss method and electrochemical testing technology, and the corrosivity of the emulsion with different types and different water content was analyzed. The results show that the corrosivity of the emulsion was lower than that of the produced water, and the corrosivity of the oil-in-water emulsion was greater than that of the water-in-oil emulsion. The oil film formed on the surface of 20 steel by the adsorption of crude oil in the water-in-oil emulsion had good integrity, which resisted the 20 steel to touch with water molecules in a certain, so the 20 steel had a light corrosion. With the increase of water content, the integrity of the oil film was gradually destroyed, and the corrosivity of the emulsion became significantly stronger. In the oil-in-water emulsion, 20 steel could directly touch with produced water. There was a dispersed oil film on the surface of 20 steel, which had a weak protective effect on metal substrate. With the increase of water content, the corrosion of the 20 steel in the oil-in-water emulsion was close to that in the produced water. The 20 steel corroded seriously at the oil-water interface, in which its corrosion behavior was similar to that in the oil-in-water emulsion.