Based on geological data and physical property data as well as processing of gravity and air-borne magnetic data, the authors, constrained by some geological information, has conducted the gravity and magnetic man-machine forward modeling in the Alongshan area. The purpose of the study is to formulate the models of underground geological bodies. The results obtained clearly show the distribution characteristics of the underground geological bodies. On such a basis, underground lithologic characteristics and structural distribution regularity can be inferred, which can serve as reference materials for regional geological mapping.