Abstarct: Panj-Kuh granitoidic body with an area of 15 Km2 is located in the northern part of Central Iranian strauctural Zone (south east Damghan). Intrusion of the pluton into the Eocene volcano-sedimentary sequence and volcanic rocks resulted in iron mineralization at andesitic host rocks. According to the exact field and petrography investigations, the initial composition of intrusive body was differentiated from the pyroxene syenite in margins to biotite syenite in the central part of the pluton, and then have been subjected to sodic-calcic (more extensive and higher temperature) and potassic (less abundance and lower temperature) mextasomatisms in the final stages. The first alteration has converted the rocks to equal combination monzonite. The sodic-calcic mextasomatism evidences characterized by extensive albite-scapolite veins throughout the pluton that change from mm to several hundered meters in wide. On the basis of petrography and microprob results, the most important mineral changes from fresh to altered rocks include in: 1) plagioclase composition either changes from andesine in the core to albite in the rim or commonly was replaced by maryalitic scapolite, 2) Sphene and magnetite have more titanium and apatite has more chlorine contents, and 3) the composition of pyroxene was remained constant. Potassic alteration which created following sodic- calcic alteration is characterized by converting pyroxene to biotite and hydrothermal K-feldspar and magnetite. The anisotropy of magnetic susceptibility technique (AMS) was used for the emplacement mechanism of the Panj-Kuh pluton. The results of this study show that the average magnetic susceptibility (Km) of the pyroxene syenite, biotite syenite and monzonite vary is from 28542, 56239 to 2173 μSI, respectively. The high susceptibility magnitudes (Km≥400SI) call for the dominance of magnetite as magnetic carriers, considered as typical of the so-called ferromagnetic granites and there is a good correlation between magnetic susceptibility and rock-type. Magnetic anisotropy percentages change from 10 to 50% through out the pluton. The highest values of P% have observed in regions with high deformation. The shape parameter values for the Panj-Kuh granitoidic body changes from -0.48 to +0.93. The main magma feeder zones have been identified by high plunge magnetic lineation and foliation stations with negative T values. Present study indicates that how magnitude of magnetic susceptibility of pluton shifts progressively from ferromagnetic behavior in the fresh biotite syenite and pyroxene syenite (presence of magnetite) to the paramagnetic behavior in the high Na-Ca mextasomatized rocks (due to removal of magnetite). It has also changed the geometry and orientation of the magnetic fabric patterns. The various magnetic data (magnetic lineation and foliation maps, K, P and T parameters), complemented by field and microstructural observations, allow us to propose that the Panj-Kuh pluton has two different types of magnetic fabric patterns. The first patterns belong to the magmatic lineation and foliation alignment that are extended parallel to the long axis of the pluton with NE-SW trend. The second fabric, which is resulted by mextasomatism as three parallel corridors, cross cut the magmatic pattern. This matter confirms with magmatic to low temperature solid state microstructures as well. The shape and magnetic fabric patterns of the pluton imply the pluton emplaced in on tension gash that formed in a sinistral shear zone.