Abstract: This paper is based on the particularity in exploration of deep salt caves. The theoretical foundation, detection principle and interpretation methods of earth electric field lithology detection(CYT) and Controlled source audio magnetic telluric(CSAMT) are discussed using the Yexian salt field gas storage project in Pingdignshan. The geometry, space distribution and feedback physical information of salt caves are studied as well. Firstly, the spatial range of target body is confirme-droughly with CSAMT method. Then the spatial form is determined in detail with CYT method on the basis of CSAMT results in favorable area. Exploration results show that the spatial form of salt cave is complex. The irregular holes appear on the geological section with depth of-1000～-1400m. But the single cavern is small and the radius is about 8～60m. The research results can be used to guide the site selection and construction of underground salt cavern gas storage, and provide some reference for deep salt caves detection and interpretation of lithology electric fields.