Abstract：At the given frequency,the apparent resistivity of magnetotelluric sounding (MT) reflects the average resistivity at the range of penetration depth of that frequency. The electro-magnetic wave with different frequency has different penetration depth. The algorithm firstly determines the subsurface resistivity and evaluates their thickness depending on the maximum frequency point and apparent resistivety;then determines the resistivity and thickness of equivalent layer parallel connecting both first and second layer;after that,the algorithm determines the resistivity and thickness of second layer from that of first and equivalent layerrand so on,finally we got the parameters of each electric layer from top to bottom. The algorithm needs neither initial model nor data fitting. The inversion of theoretic data with different model showed that the method is effectiveness in dividing conductive formation. The inversion results and the real models matched well.
