The work aims to study the inhibition performance of cinnamyl imidazoline as inhibitor of N80 steel in hydrochloric acid. A cinnamyl imidazoline was synthesized using solvent method, with cinnamic acid and N-hydroxyethyl - ethylenediamine as raw materials and aluminum oxide as catalyst. The molecular structure of the product was characterized by means of UV spectrum and IR spectroscopy. Inhibition performance of the imidazoline corrosion inhibitor of N80 steel in hydrochloric acid was studied by virtue of static weight-loss measurement, polarization curves and electrochemical impedance spectroscopy, and the corrosion inhibition mechanism was also discussed preliminarily. The results of weight-loss measurement indicated that inhibition efficiency of the investigated compound was found to depend on mass concentration of the inhibitor. The corrosion inhibition efficiency was stable and up to 86.9% as imidazoline mass concentration reached 400 mg/L. Corrosion rate increased with the increase of temperature, and the corrosion inhibitor had good inhibition efficiency when the temperature ranged from 30 ℃ to 50 ℃. The results of polarization curves indicated that the inhibitor was mixed-type inhibitor which worked to control anodic reaction with geometric blanketing effect. The analysis of electrochemical impedance spectroscopy implied that the inhibition efficiency increased with the increase of corrosion inhibitor mass concentration and suppressed corrosion of carbon steel in HCl medium significantly. Cinnamyl imidazoline is an effective corrosion inhibitor of N80 steel in HCl medium.