A kind of imidazolinyl quaternary ammonium salt was synthesized with oleic acid, tetraethylenepentamine and benzyl chloride. Then it was transformed into high watersoluble corrosion inhibitor by reaction with organic acid. Some factors, such as the mole ratio of raw materials, reaction time and reaction temperature affecting the anticorrosive capacity of the inhibitor were discussed. As a result, the optimum synthesis conditions is listed below: the molar ratio of organic acid to imidazolinylquaternary ammonium salt 1.1, reaction time 3 h and reaction temperature 150 ℃. The imidazolinebased corrosion inhibitor synthesized under these conditions has better watersolubility, and the corrosion inhibition efficiency to carbon steel is above 85% in the mass of hydrochloric acid aqueous solution is 15% at 90 ℃.