Abstract: Decanoic acid imidazoline quaternary ammonium salt (DI) corrosion inhibitor was obtained by reaction using decanoic acid, diethylenetriamine, and benzyl chloride as raw materials. The corrosion inhibition performance of DI on N80 steel in a 1% hydroxyethylenediphosphonic acid (HEDP) solution was evaluated by weight loss mothod, SEM, and electrochemical testing. The results show that when the DI concentration was 400 mg/L, the corrosion inhibition rate reached 74.94%. The scale inhibition performance of DI on calcium carbonate in 1% HEDP system was studied using static deposition method. The results show that the addition of DI improved the scale inhibition effect. When the concentration of DI was 600 mg/L, the scale inhibition efficiency could reach 93.64%, which was about 10% higher than when DI didn′t add. The adsorption behavior of DI and HEDP on the crystal planes of calcite (104) and (102) was studied through molecular dynamics simulation.