考虑大地的有限导电率时，大地附近的水平电场对电源线和电子设备的影响更为显著，因此，在假设大地为完全导 体的情况下推导出来的雷电电磁场传输线方程需进行修正. 利用修正过的传输线方程以及大地的各种参数，经过计算得到雷电过电压在传输线上的传播情况，并对大地有限导电率的影响作了讨论分析.

Considering the finite conductivity of the earth，the horizontal electric field of the near earth is more significant influence on the power cord and electronic equipment. Therefore，the earth conductor is supposed to be a noble ideal，in this case，the transmission line equation of the lightning electromagnetic field is derived，which needs to be revised. We use the modified transmission line equation and the various parameters of the earth and get the spread of lightning overvoltage on the transmission line. The impact on the limited earth conductivity is discussed and analyzed.