Abstract: To improve the detection level of foundation piles and reduce major potential safety hazards, this study established three geoelectric models corresponding to a single pile, long-short piles, and a pile group through the 2.5D forward and inverse numerical simulations using the cross-well ultra-high-density resistivity imaging technology and analyzed the response characteristics and regularity of these models. Given the complex detection environment of foundation piles, this study further expounded the application characteristics and effects of the technology by combining two cases for the detection of the burial depths of piles. The results are as follows. The cross-well ultra-high-density resistivity imaging technology enjoys the advantages of high precision and flexible and convenient construction when being applied to the detection of pile buried depth. It can detect the lengths of foundation piles on a large scale rather than detecting one foundation pile using one detection hole, thus greatly improving the detection level of the burial depths of foundation piles.