The Stratagem ^TMEH-4 electrical conductivity image-forming system is a magnetotelluric sounding system which combines partly controllable source and natural field source and consists of receiving device and emitter. Based on the exploration object, one can use high-frequency allocation (10 Hz～100 kHz) or low frequency allocation (0.1 Hz～1000 Hz). By collecting two sets of electromagnetic signals (E_x, H_y, E_y, H_x) in time domain which are perpendicular to each other and through spectral analysis and calculation, the variation curves of different frequencies, resistivities, phases and correlation degrees can be drawn. By analysing and comparing these curves, the on-the-spot judgement of data quality can be carried out, the EMAP two-dimensional continuous profiling inversion can be conducted for continuous inversion result of one-dimensional apparent resistivity of measuring points along the profile, and the gray level diagram of the resistivity section can be illustrated. As a result, preliminary interpretation of the exploration result may be made immediately.Three fields work examples are given in this paper.