Using the large-scale middle gradient sweep ladder, the authors rapidly delineated the distribution of anomalies. IP sounding device was adopted to detect space state of the polarization body, and frequency spectrum characteristics of IP field were used to distinguish graphite-bearing marble from metal sulfides. Based on comprehensive geophysical exploration in combination with geological conditions of the ore deposit, the dual-frequency IP method has achieved good results in the exploration of a gold-copper deposit in southwest Henan Province.