The IP method based on the difference in the polarizability and resistivity of rocks has played an important role in the exploration of concealed and deep ore bodies. This paper points out that, with the IP sounding, the medium-gradient array can find and delineate IP anomalies and detect the burial depth and spatial occurrence of polarized bodies, thus providing fairly sufficient basis for engineering verification. The combined methods also played an important role in search for large-sized lead-zinc-silver polymetallic ore deposits in Caijiaying and Beichagoumen of Hebei Province.