根据电磁场理论，推导出检测线圈所产生磁场的计算模型。采用ANSYS有限元软件，对涡流检测薄板内气孔型缺陷的磁场进行了数值模拟。通过仿真靠近下表面的小气孔，来确定检测该薄板的最佳激励频率。针对不同直径、不同深度的气孔，分析对应的阻抗改变值的幅值和相位角的变化规律。得出的结果与理论相吻合，可以为涡流检测的定量定性分析提供有意义的参考依据和分析方法。

Based on the theory of electromagnetic-field, the calculation model of magnetic fields generated by detecting coil is deduced. This paper simulates the magnetic-field of eddy current testing of sheet steel with inner air holes. The aim is to determine the best drive frequency of testing the sheet steel by simulating the small air hole near the lower surface. According to the air hole with different diameter and different depth, analysis is made of the change rule of amplitude and phase of corresponding impedance. The result that we got is identical to the theory of electromagnetic-field, this can provide a meaningful reference and analysis method for the quantitative analysis and qualitative analysis of eddy current testing.