应用直流电位梯度法对埋地管防腐蚀层缺陷进行定位和尺寸检测，分析了埋地管防腐蚀层缺陷上方地表电位差的分布规律以及缺陷直径与地表电位差的关系，基于试验研究结果建立了埋地管防腐蚀层缺陷的三种校核计算方法，并对其准确度进行了比较。结果表明：地表电位与缺陷上方通断电电位差的比值、地表电位和地表电位等势线半径均与防腐蚀层缺陷直径呈现较好的线性关系，拟合优度均高于95%；三种直径校核计算方法中， ΔU/ΔE[]D 的准确度最高， ΔU[]D 的次之， R[]D 的最低，双缺陷校核计算的准确度明显优于单缺陷校核计算的。

The directed current potential gradient method was used to detect the location and size of the buried pipe anti-corrosion coating defects. The distribution regulation of the surface potential difference above the buried pipe anti-corrosion coating defect and the relationship between defect diameter and surface potential difference were analyzed. Based on the experimental research results, three checking and calculating methods for the defects of buried pipe anti-corrosion coating were presented, and their accuracy was compared. The results show that the ratio of surface potential difference to on-off potential difference above the defect, surface potential difference and surface potential gradient equipotential line showed a good linear relationship with anti-corrosion coating defect diameter, and their fit goodness were higher than 95%. Among the three diameter checking calculation methods, the accuracy of ΔU/ΔE/D was the highest, ΔU/D was the second, and R/D was the lowest. The accuracy of double defect check calculation was obviously better than that of single defect check calculation.