Abstarct: Darreh-Bagh granitoidic pluton is located in the 10 km of NW Aligudarz and is intruded in low to moderate grade mextamorphic rocks of early Jurassic with compositional range of slate, phyllite and schist. baxsed on the field and petrographical studies, Darreh Bagh granitoidic pluton includes lithological composition range from granodiorite, granite to leucogranite, aplite and tourmaline bearing pegmatites. Granodiorites are the main component of this pluton. Granites are cut granitoids as apophyse and dike and those are younger than granodiorites. baxsed on the mentioned evidences, granodioritic magma are differentiated and then evolved to granitic magma and in the later stage they are evolved to silica rich magmas and rich in B (Boron) and finally resulted in to formation of tourmaline bearing leucogranites to rich of tourmaline. Tourmaline bearing pegmatites formed in the final stages of Darreh Bagh granitoidic pluton differentiation. Silica veins resulted of intensively fractional crystallization of granitic magmas. Wide range of lithological composition show that has been took placed extensive fractional crystallization in Darreh Bagh granitoidic pluton. For the first time, emplacement mechanism of the mentioned pluton, investigated by anisotropy of magnetic susceptibility (AMS) method. baxsed on the geochemical characteristics of Darreh Bagh granitoidic pluton has peraluminous and calc-alkaline nature and is belong to S and CAG type granitoids. We took 325 cores and 1200 samples from 121 stations. Magnetic parameters of these samples have been measured in the magnetic lab of Shahrood University of Technology by MFK1-FA kappabridge machine. The resulted data indicate that mean magnetic susceptibility in µSI are as follows: granodiorites (285), leucogranites (47), migmatites (434), and surmicaceous enclaves (389). baxsed on these values, Darreh Bagh granitoidic pluton is a paramagnetic granitoids (500>km>0 in µSI) (equal to S-type). This characteristic confirmed by the presence of ilmenite in thin-polished sections and thermal magnetic diagrams. Magnetic foliations mainly show N33E/28 NW trend which this is accommodate with big structures such as big faults and axial planes of folds. The percentage of anisotropy (P %) values vary from 2 to 10 and show positive correlation with degree of deformation. Shape parameter (T) values vary from -0.58 to 0.78 and then most of magnetic ellipsoids are oblate. The percentage of magnetic anisotropy (P) and shape parameter (T) values increased from west to east and this conclusion accommodate with increasing of deformation in this direction. baxsed on the magnetic parameters and their interpretations it is possible to divide DGP to A and B domains and A1, A2 subdomains. In these subdomains magnetic lineations oriented to the north. In the middle part of this pluton (B domain) magnetic lineations dominantly oriented to the east and southeast. baxsed on distribution patterns of magnetic lineation these to domains emplaced with short delay compared to each other's. Meanwhile, emplacement of A domain was precursor to B domain. Whit attention to distribution patterns of magnetic lineation and foliations, principles of interpretation of magnetic parameters and regional geological characteristics, was emplaced in form of one relatively large sill in a dextral shear zone (in relation to a transpression regime).