The De'erni copper and cobalt ore deposit was found in the 1950's and has been explored since then. Nevertheless, no breakthrough has been achieved near the main ore body. It is hence necessary to find some effective geophysical methods to solve the difficulty. By means of numerical calculation and field test, this paper deals with the availability of TEM in detecting underground ore bodies. Tests with TEM show that strong anomalies appear over massive copper-bearing pyrite ore bodies, and low resistivity is obvious on the cross section through inversion. Based on these achievements, the authors consider that TEM is a useful method in search for ore bodies in the vicinity of known ore deposits.