Abstract: High-precision magnetic measurement has been broadly applicated in geological surveying.The magnetic data are advantageous in geologic mapping,geologic boundry delineating,ore-body outlining,as well as ancient tomb and buried gallery searching.When mapping in concealed areas,high-precision magnetic measurement can decide not only strongly magnetic rocks' boundary,but also weakly magnetic rocks' boundary.On the premise of increasing the information density,the weakly magnetic orebodies in typical metallogenic provinces can be outlined simply by the different magnetic susceptibilities and residual magnetization.Some examples are given,such as the delineating of the boundary between Dashiqiao and Gaixian formations of Liaohe group in Jinshangou gold field,and the delineating of the boundary between the granite and the felsic mylonite in Fuxin.