The present disclosure relates to an ERT/ECT dual-modality combined three-dimensional sensor. A cover box is sheathed with a shielding box, a plurality of small round holes are formed in the top surface and the side surfaces of the cover box, ERT electrodes are arranged in the small round holes, and ECT electrodes are arranged at the outer sides of the ERT electrodes. The ERT electrodes are connected to an ERT data acquisition box via electrode leads, and the ECT electrodes are connected to an ECT data acquisition box via the electrode leads. An integrated cuboid design in line with the concrete structure is employed. Meanwhile, the dimensions, combination modes, placement modes and positions, supporting structures, shielding devices, electrode leads and leading-out modes of two sets of electrode arrays are subjected to comprehensive optimization design to achieve three-dimensional visual nondestructive monitoring of the moisture intrusion process in the concrete structure.