Abstract: In the exploration of deep concealed orebodies, the large distance between the iron orebody and the observation surface may produce only one broad magnetic anomaly which can't distinguish ore?related anomalies and background?induced anomalies. The appli?cation of upward continuation and derivatives fails to obtain satisfactory results. During the case study in Qinghai Province using down?ward continuation, the authors obtained the fine anomalies based on the downward continued field with a distance of 30 times that of the grid interval. The comparison of the downward continued field with many magnetite?bearing and non?magnetite?bearing drill holes re?vealed a clearer relationship between the magnetic anomalies and the ore?intersecting drill holes. It is also shown that all of the non?magnetite?bearing drill holes are located outside the downward continued field. Since it is possible to apply the stable downward continu?ation at present, the authors hold that the downward continuation of the anomaly with a large buried depth is useful in distinguishing su?perimposed anomalies and detecting the anomaly's location, thus providing evidence for planning the mining operations. The exploration accuracy is also discussed in this paper.