Abstarct: Magnetometry is one of the most important geophysical techniques widely used in exploration. Therefore, collecting, interpreting and modeling these data are of particular importance. Magnetometry is considered as one of the most important steps in detailed pre-drilling exploration. The theory of magnetic effects on local geological environments can be used as a qualitative guide for exploration and prediction of anomalies oscillation patterns. By predicting these models, one can evaluate magnetic effects of deposits. The alteration zones surrounding porphyry copper deposits (center to margin) are usually potassic, phyllic, argillic and propylitic, respectively, containing different amounts of iron minerals including magnetite. It is clear that revealing hidden mineralization system by erosion can significantly change magnetic effects of the ore deposit. According to these features of deposits, one can determine the type of alteration zones, alteration stage and erosion level using magnetometry in order to trace potossic zone which contains the largest ore concentrations. In the present study, first artificial models with a spherical structure were made at various erosion levels. Then, using the geological model of porphyry copper deposits, magnetic effects at different erosion levels were modeled and compared with each other. Then, the data collected from two porphyry copper deposits of Masjed Daghi and Ghahan were analyzed. To this aim, magnetic data were corrected and then different filters such as reduction to pole, upward continuation and derivatives were applied. The anomalies in the region were identified and compared with porphyry copper models to determine the erosion level.