It is a difficult problem to accurately survey underground caves in the regions characterized by complicated engineering geological and sophisticated geophysical conditions. The cave of Yuanjiacun iron mine features various sedimentary facies and is the focus area for this study. A high-density resistivity method is used to study the accurate survey methods of the cave under complicated engineering geological conditions. The resistivity of the iron ore in the major sedimentary facies is measured using the outcrop method. The results indicate significant resistivity differences among different sedimentary facies. The oxide facies has a high resistivity, and the silicate facies has a low resistivity. Cave investigation forward models for the caves that occur in each sedimentary facies are developed. The forward calculations identify the resistivity anomalies of the caves for the various sedimentary facies. Furthermore, the resistivity characteristics are more evident in the low-resistivity silicate sedimentary facies. Differences in the reflection of caves exist among different arrays, particularly the dipole array more evident. The high-density resistivity method is used to survey the site and the potential safety risks are eliminated by accurately identifying two caves by their resistivity anomaly characteristics.