In order to prevent geological disasters and improve urban planning, it is of great significance to explore the distribution of hidden structures in Zhenzhou and its surrounding areas by audio magnetotellurics (AMT). In this paper, an EW-trending AMT profile was set up on the east of Laoyachen fault in the northern suburb of Zhenzhou. Noise reduction, rotation, impedance analysis and static correction of the original data were processed. The 2D regularization inversion theory method, i.e., nonlinear conjugate gradient method (NLCG) was used. The initial mode was constrained by seismic layering results, which was nearly in parallel with the AMT profile, which reduced the multiple solution and the NLCG's dependence on the initial mode. Good electrical results were obtained, which show that there are three layers and a hidden structure in the profile. At the same time, combined with geological and geophysical data, the authors inferred the explanation. It is inferred that the hidden structure may be a normal fault developed in Late Neogene or an unconformable contact surface between Quaternary and Neogene strata. The results obtained by the authors provide the geophysical and technical basis for further exploration of urban hidden structure.