利用电化学阻抗谱技术,研究X70钢的最佳阴极保护电位随土壤中Cl-和含水率的变化.结果表明:在Cl-含量<10 mmol/kg时最佳保护电位随着含水率的增加先升高后降低,变化幅度在150 mV左右;Cl-含量≥10 mmol/kg时,最佳保护电位随着含水率增加呈现降低的趋势;Cl-含量为20 mmol/kg时的不同含水率的土壤中最佳保护电位均达到最小值;随着含水率的升高Cl-对最佳保护电位的影响逐渐减小. Electrochemical impedance spectroscopy (EIS) was used to study the optimum cathodic protection potential of X70 steel with the change of Cl- and water content in soil. The results showed that the best protective potential of X70 steel increased with the increase of water content First increased and then decreased, with a variation range of about 150 mV. When Cl-> 10 mmol / kg, the optimal protective potential decreased with the increase of water content. When the content of Cl- was 20 mmol / kg, The best protective potential in soil reached the minimum value. With the increase of moisture content, the effect of Cl- on the optimum protective potential decreased gradually.