The resistivity-depth information is the basic data for many applications in power system, such as designing a HVDC grounding system, assessing the electromagnetic influence between pipelines and power lines, and calculating the transmission line impedance. In this paper, the Occam inversion method is used to obtain underground resistivity information. The method and theory of this inversion is introduced in the first place. The objective function of the inversion is constituted by the fitting difference and model roughness through the Lagrange multiplier; and is solved by iteration and local linearization method afterwards. According to the horizontal electric field data on the ground surface at different frequencies, the corresponding results based on known electric fields are inverted accordingly. The results show that the Occam inversion can meet the requirement of inversion accuracy, and the resistivity-depth information can match well with the selected geo-electric models. Meanwhile, this method is less affected by the initial model, and is proven to be an effective inverse method. The Occam inversion can served as another candidate to invert the soil information, compared with its counterpart, Wenner four-electrode method.