The Razan (Hamadan) area is located about 300 Km of southwest of Tehran. The southern part of this area is belonging to Sanandaj-Sirjan and northern part belongs to Central Iran zones. The marine deposits of Oligo-Miocene (Qom Formation) are well distributed in the area. Lavas and volcanoc1astics are important parts of Qom Formation. These parts exposed in vast bond which has a SE-NW direction like general Zagros zone trend. Petrological study of lavas in Qom Formation is the most important aim in this research and it's based on field observation, petrographical and geochemical (XRF, Isotopic geochemistry and SEM analyses) study. This research show that extrusive rocks of studied area are dacite-ryodacite, andesite, trachyandesite, homblend andesite, basaltic andesite and trachybasalt. It also revealed that different phenomena like contamination and probably magma mixing had affected on extrusive rocks magma formative.