XJ Mannich bases were synthesized with formaldehyde, acetophenone, aromatic hydrazine as raw material. Through orthogonal experiments the optimum synthesis conditions was obtained as follows: the reaction temperature was 70℃, the molar ratio of formaldehyde to aromatic hydrazine was 2.9:1, the malor ratio of acetophenone to aromatic hydrazine was 3.2:1, the pH value was 4 and the reaction time was 6 hours. The Mannich base prepared by the optimal recipes was named as XJ-3. The inhibition action of XJ-3 Mannich base on N80 steel was investigated by means of mass loss and electrochemical techniques. It was showed that the corrosion rate of N80 steel was 0.256 g·(㎡·h)-1 in 15% hydrochloric acid containing 1.0% of XJ-3,which was lower than the first Grade Standard of SY/T 5405-1996. Electrochemical test results showed that, the XJ-3 Mannich base belonged to a mainly anodic-controlling composite corrosion inhibitor. XJ series corrosion inhibitor effect was further confirmed by AC impedance technique. The adsorption behavior of the XJ corrosion inhibitor on the surface of N80 steel was subject to Langmiur adsorption isotherm.