In this paper, the Dongchuan-type copper deposits are taken as an example to illustrate the application of GIS to the geo-anomaly-based delineation of mineral resources. The following eight steps are listed in this paper to delineate the permissive and preferable ore-finding areas: (1) the analysis of favorable prospecting index using linear and planar geo-anomalies; (2) the analysis of favorable prospecting index using combined anomalies; (3) the construction of a GIS-based spatial model for mineral prognosis; (4) the delineation of the permissive ore-finding area; (5) the determination of the synthetic anomalies and numerical range for the prediction of the favorable prospecting areas, and the determination of the weights of these two variables; (6) the superimposition of all the selected anomalies and the construction of the superimposition map; (7) the determination of unifying criterion of favorable prospective areas at various levels, and (8) the delineation of favorable prospective areas. Finally, this paper offers a detailed discussion of the results in the forecasting of Dongchuan-type copper deposits.