Abstarct: SW Mayamey granitoidic plutons are a part of the northern margin of Central Iran structural zone. Field observations and petrographical studies indicate that the compositional rang of this granitoids composed of granodiorite, granite, alkalifeldspar granite¬ and leucogranite¬.¬ With attention to carried out petrographical studies biotite plagioclase, orthoclase and quartz are major minerals and apatite, sphene and zircon are minor minerals. In this area and neighboring area with similar historical geology granitoidic plutons such as Band e Hezar Chah have been covered by a thich detrital –sedimentary sequence with mainly conglomerate nature.. This detrial- sedimentary sequence in the lower part contains intercalations of shales with plant fossils and sandy limestones bearing ammonite that indicates late Triassic - upper Jurassic age for this sequence. The conglomeratic part is dominantly composed of granitic pebbles that originated from above granitoid plutons. Since these granitoid plutons were covered by this sequence and with respect to recent dating of this plutons (Middle Jurassic), we conclude that their age is older than Jurassic and the previous age is wrong. This plutons intruded by two classified diabasic micro dioritic- micro gabbroic dikes with late Neoproterozoic- early Cambrian age and Middle jurassic age. Earlier dikes are highly deformed and alterated whereas younger (or later) dikes frequently are undeform and rarely alterated. Negative anomalies of Ti, P, Nb and enrichment of LREE and incompatible elements such as Rb, Th and U and abundance of biotite in this granitic rocks indicate that these rocks have been generated from partial melting of mextapssamites and mextapelites and they have peraluminous and high K nature, and then belong to S- type. These plutons formed in an ancient accretionary prisms tectonic setting in the location of the collision of old microcontinents. This plutons have been formed in result of replacement molten masses with composition andezitic- basaltic inside the mextamorphic rocks(with compositional range from micaschist to garnet-bearing gneiss) and their following thermal effects(Anatexis) around 540 My age. This age range is baxsed on the U-Pb age dating on the intrusive plutons with similar historical geology such as Delbar and Band e Hezar Chah.