1. Shanghai Branch of China National Offshore Oil Corporation Limited, Shanghai 200030, China;
2. Liaohe Oilfield Branch of China Petroleum, Panjin 124010, Liaoning, China

In order to obtain the distribution feature of geological bodies by the magnetic gradient data clearly and correctly, the authors use total horizontal derivative of analytic signal and gradient Euler deconvolution methods to interpret aeromagnetic gradient data. The maximum of the total horizontal derivative of analytic signal method can define the distribution of the ore bodies, and gradient Euler deconvolution can avoid the interference of background anomaly, and obtain the location and depth of the magnetic source correctly. Theoretical tests show that the combination of total horizontal derivative method and gradient Euler deconvolution method can obtain horizontal range and depth of the magnetic source correctly. The authors apply the presented methods to interpret magnetic gradient data in Qian'an area of Hebei, and delineate five larger iron ore resources in banded distribution, with burial depths of 200 m to 450 m.