With the development of extra high voltage power grid

electromagnetic radiation arouses people’s intensive concern.With an engineering example: physical discomfort of teachers and students in primary school near a 500 kV AC transmission lines

distribution of power frequency electric field and power frequency magnetic field under the lines is analyzed with program based on charge simulation method（CSM） and simulation current method（SCM） respectively.Moreover

measured data indicate that electric field intensity on the roof of the teaching building partially approaches national public exposure limit in good weather condition;it exceeds the limit in bad weather condition（high relative humidity）.The solution proposal for unsafe electric field environment is to fix three shielding lines（LGJ-50/30） to reduce electric field strength from 3.43 kV/m to 1.35 kV/m.Even in rainy weather condition

electric field strength also meets the national standards’ request.