The work aims to investigate corrosion inhibition effect of imdidazoline inhibitor CPA-1 on N80 steel in 3.5%NaCl solution saturated CO2. The relationship between inhibition efficiency and inhibitor concentration at different temperature was studied in the method of weight-loss, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. Surface morphology was observed and analyzed with scanning electron spectroscope (SEM) and scanning electrochemical spectroscope (SECM). Adsorption type of imidazoline inhibitor on the surface of N80 steel was studied based upon isothermal adsorption model. Weight-loss results showed that inhibition efficiency of imdidazoline inhibitor increased as inhibitor concentration increased, it reached 95% when the concentration was 250 mg/L at 40 ℃, and inhibition efficiency decreased to 87% slowly at 80 ℃. Electrochemical tests indicated that imdidazoline inhibitor could inhibit both catholic and anodic reaction. Surface morphology analysis showed that the corrosion inhibitor could improve corrosion degree of metal surface effectively. Imdidazoline inhibitor CPA-1 acts as a mixed-type corrosion inhibitor and exhibits good corrosion inhibition for N80 steel. Inhibition mechanism of imdidazoline inhibitor is to prevent metal corrosion by forming one layer of adsorption film on metal surface in the method of adsorption, and the absorption obeys Langmuir adsorption isotherm. Both physical adsorption and chemical adsorption are possible on metal surface.