Abstract: To reveal the fine geological structure in the deep Litun iron-rich deposit in the thick coverage area, distributed three-dimensional wide field electromagnetic detection was carried out. It uses high-order 2ⁿ sequence pseudo-random signal, can transmit 49 frequencies at a time and receive at the same time, realize distributed rolling measurement, and obtain the geoelectric characteristics of 2000m underground. Based on this, a detailed interpretation of the underground geological structure was carried out, and a three-dimensional geological model of the key research area was constructed. The interpretation results were in good agreement with the existing seismic and drilling information. It provides effective constraints for gravity-magnetic joint inversion and delineates new prospecting targets in combination with metallogenic laws. The results show that the distributed three-dimensional wide field electromagnetic method is an effective detection method to obtain the deep fine geological structure in the thick coverage area and has a good application prospect.