The invention relates to rapid judgment for the corrosion of a sodium bicarbonate water type oil well, which is applied to the corrosion treatment of a pit shaft of the oil well. A production liquid is of a sodium bicarbonate water type. When the mole ratio of Ca to HCO3- is between 0 and 1 and less than 0.6, the corrosion which is local corrosion and scale formation coexist; along with the increase of the mole ratio of the Ca to the HCO3-, the scale formation of the pit shaft is relieved, but the corrosion becomes serious; and when the mole ratio of the Ca to the HCO3- is greater than 0.6, the pit shaft of the oil well is mainly corroded. The corrosion condition of a sodium bicarbonate water type medium is fast known through the mole ratio of the Ca to the HCO3-. A corrosion inhibitor for the sodium bicarbonate water type medium is made from the following components in percentage by weight: 20 to 35 percent of carboxylate sodium imida, 20 to 35 percent of water-soluble rosinyl imidazoline, 5 to 10 percent of dodecyldimethylbenzylammonium chloride, 0 to 5 percent of aminotri-methylene phosphonic acid, 0 to 5 percent of hydroxyl ethidene diphosphonic acid, 5 to 10 percent of methanol, 2 to 5 percent of dispersant and the balanced of water. The rapid judgment and the corrosion inhibitor can improve the efficiency of corrosion inhibition.