Thiourea base rosin imidazoline quaternary ammonium salt was synthesized with raw material which are rosin, diethylenetriamine, 3-chlorinum-2-hydroxyl propane sulfonic acid sodium and thiourea, and the structure of thiourea base rosin imidazoline quaternary ammonium salt was characterized by FT-IR and 13C NMR. The corrosion performance of thiourea base rosin imidazoline quaternary ammonium salt was studied by static weight-loss method and electrochemical method through acidic medium, and the mechanism of homemade corrosion inhibitor was explained by the theory of film forming and the molecular structure of the corrosion inhibitor. The results showed that the inhibition efficiency could reach 90.81% in the mass fraction of 15% hydrochloric acid and add the quality of hydrochloric acid 0.4% imidazoline corrosion inhibitor at 30℃, and the homemade inhibitor was adsorped on the surface of carbon steel mainly by adsorption founction.