Through casing resistivity measuring device

The invention relates to a through casing resistivity measuring device, which comprises a wellhead metal casing, an underground probe and a ground power supply, the ground power supply is connected with the wellhead metal sleeve through a lead, and the underground probe is arranged in the wellhead metal sleeve; a wellhead metal sleeve is used as an emission electrode; the downhole probe includes a plurality of electrode modules and an insulating mandrel. Another measuring device comprises: a downhole probe, wherein the downhole probe comprises a plurality of electrode modules and an insulating mandrel; the underground probe is provided with array electrodes, a current return passage is constructed between the array electrodes of the underground probe, and a plurality of working frequencies are adopted. The through-casing resistivity measuring device can utilize a ground high-power power supply to directly supply power through the metal casing, the power supply power is not limited by the underground environme