The magnetite resource investigation and drilling verification in Linfen shows that the magnetotelluric sounding method has the advantage of detecting deep highconductivity layer, and hence is effective in prospecting for deep and concealed ore deposits. With a practical example, the authors revealed the relationship between borehole data and low resistance contour lines, and delineated the top and bottom interfaces of the ore body at the depth of 1 400 m as well as the position of the orecontrolling fault. The results show that the inferred depth is consistent with borehole data, with the errors for the top and the bottom being only 3.8% and 0.5%. This is a successful example in the application of the frequencydomain electromagnetic sounding method.