Cationic imidazoline quaternary-ammonium-salt was synthesized as a corrosion inhibitor of reinforced concrete by means of the molecular structure design. Then,its molecular structure and corrosion inhibition performance on the steel reinforcement in the simulated concrete pore solution with 3.5% of NaCl were characterized,and the corresponding corrosion inhibition mechanism was preliminarily discussed. The results indicate that ( 1) the synthesized product is consistent with the designed molecular structure,and the corresponding yield is up to 95%; ( 2) the synthesized imidazoline quaternary-ammonium-salt is a cationic corrosion inhibitor with a good inhibition effect on the corrosion of steel reinforcement in the simulated concrete pore solution,specifically,the corrosion inhibition effect of the salt with a dosage of 1. 0% is slightly inferior to that of the inorganic corrosion inhibitor sodium nitrite with a dosage of 2. 0%,while that of the salt with a dosage of 2. 0% is superior to that of the alcohol-amine organic corrosion inhibitors with the same dosage; ( 3) the salt with a dosage of 1. 0% displays a better corrosion inhibition effect in the early and middle stages ( 1,7,14 d) ,while the salt with a dosage of 2. 0% does after 28 days; and ( 4) the corrosion inhibition mechanism of the salt can be described as the adsorption and film-forming on the steel surface and the inhibition of the cathodic reaction of the steel reinforcement.