The invention discloses a whole-zone electric coupling source frequency domain magnetic sounding method and a device thereof; the magnetic sounding method comprises the following steps: (1) a transmission power source (generating set) is arranged, the transmission power source is connected with a multiple frequency current transmission machine and the multiple frequency current transmission machine is connected with two current-supply electrodes A and B; (2) a transmission-reception distance r is selected, a reception magnetic probe is arranged and is connected with a reception machine; (3) the transmission power source, the multiple frequency current transmission machine and the reception machine are started, the multiple frequency current transmission machine transmits the current of designated wave form, voltage, volume as well as frequency to the underground via the current-supply electrodes A and B, the reception machine measures the magnetic field responses of each frequency component from the underground simultaneously, the relevant parameters are automatically stored into a memory and the apparent resistivity of near zone, far zone and medium zone can be automatically calculated respectively according to relevant formulas, automatically drawn out and stored. The invention also comprises the corresponding devices. The whole-zone electric coupling source frequency domain magnetic sounding method is suitable to be used for underground electrical distribution observation in the whole zone (including the near zone, the medium zone and the far zone), used for investigating underground geological structure and mineral product distribution or solving other engineering, hydrological as well as environmental geological problems, and has high observation efficiency, high accuracy and simple equipment.