Abstract: The paper analyses the size of gravity and magnetic anomaly caused by magmatic rock invasion under condition of certain parameters, such as magnetic susceptibility, density, the buried depth of the top, horizontal scope and vertical extension, and introduced the resolution ability of existing gravity exploration instruments and magnetic exploration instruments. Combining with the size of gravity and magnetic anomaly caused by magmatic invasion, the authors discussed some concrete requirements for the working layout of gravity and magnetic exploration work and instrument operation methods in order to create the most favorable preconditions for acquiring geophysical anomaly caused by magmatic rock invasion, so as to locate magmatic intrusive mass in coal mining area.