According to the 1:200000 regional gravity data in northwest Hebei, this paper deals with the application of regional gravity survey to the exploration of intrusive bodies in northwest Hebei. Based on a detailed study of the gravity anomalies in this area, the authors delineated several important rock bodies and, on such a basis, generalized the gravity and magnetic field marks for qualitative interpretation of magmatic rocks and their modes of occurrence. In addition, geological-geophysical models for several kinds of intrusive bodies were formulated, and new understanding concerning the distribution characteristics of the magmatic rocks in this area was put forward.