Abstract: According to the issue that noise had an important influence on the solution of initial field intensity with the receiving field intensity of different probing lin es within a sector in the process of radio electromagnetic wave tunnel perspective,a new thought was put forward to solve initial field intensity by all receiving field inten sity in the whole working face,and the method that initial field intensity was solved with classified probing lines was explored. Firstly,the receiving field intensity of the s ame probing lines was classified. Then the approximate background receiving field intensity of every probing line was obtained by classified receiving field intensity. Aft er the equations of the attenuation formula of electromagnetic were established,the initial field intensity and background absorption coefficient were obtained by least s quare method. Theoretical analysis showed that the method could make full use of all of the receiving field intensity in the whole working face. The error of solved result with this method was about 5%,and it could meet the requirements of mineral exploration,served as a guideline on the solution of initial field intensity.