以乙醇水溶液为提取剂从空心莲子草中得到提取物（APE），并用红外光谱（FTIR）和紫外光谱（UV）表征了APE的官能团和UV吸收曲线。利用失重法、电化学法、扫描电子显微镜（SEM）观察、接触角测试等研究了APE在0.50 mol/L HCl溶液中对冷轧钢的缓蚀性能。结果表明：APE对冷轧钢在HCl溶液有显著的缓蚀效果，50℃ 100 mg/L APE的缓蚀率高达97.1%；缓蚀率随缓蚀剂量的增大先增大后趋于平稳，随温度升高稍有增加。APE为混合抑制型缓蚀剂，其在冷轧钢表面的作用机理为“几何覆盖效应”；添加APE后电荷转移电阻显著增加，但界面双电层电容值下降。APE在钢表面的吸附符合表观Langmuir吸附等温式，吸附方式既存在化学吸附又有物理吸附；SEM观察和接触角测试结果表明，APE显著减缓了冷轧钢表面的腐蚀，且增强了其表面的疏水性。

Alternanthera philoxeroide extract (APE) was obtained using ethanol aqueous solution as extractant, and the functional groups and UV absorption curves of APE were characterized by infrared spectroscopy (FTIR) and ultraviolet spectroscopy (UV). The corrosion inhibition performance of APE on coldrolled steel in 0.50 mol/L HCl solution was studied using weightlessness method, electrochemical method, scanning electron microscope (SEM) observation, and contact angle test. The results showed that APE had a significant corrosion inhibition effect on cold rolled steel in HCl solution, and the corrosion inhibition rate of 100 mg/LAPE reached 97.1% at 50 ℃. The corrosion inhibition rate increased firstly and then stabilized with the increase of the corrosion inhibitor dose, and slightly increased as the temperature increased. APE was a mixed corrosion inhibitor, and its electrochemical mechanism on the surface of cold-rolled steel was “geometric coverage effect”; the charge transfer resistance increased significantly after the addition of APE, but the capacitance value of the electric double layer at the interface decreased. The adsorption of APE on the surface of steel conformed to the apparent Langmuir adsorption isotherm. There were both chemical adsorption and physical adsorption. SEM observation and contact angle test results showed that APE significantly slowed down the corrosion of cold-rolled steel and enhanced the hydrophobicity on the surface of the cold-rolled steel.