Introduction of Islam to Iran changed the political and social structures, as well as part of the social stratification system. The present article deals with the effects of the introduction of Islam on the social stratification of Iran from the fall of Sasaninan to the end of Omavids era. The main question concerns the roles of the political, economic and social-cultural structure of Iran- from the introduction of Islam to the end of the Omavids- in the continuation or change of the social stratification system. The main hypothesis is that the introduction of Islam changed the social stratification system as a result of the changing political and socio-cultural structures. The sociological method used in this study was taken from Ted Kachel, and the theories were from Talcott Parsons, Guy Rocher and Max Veber. It has also been organized on the basis of the stratification system and the division of the social classes of Iran after the introduction of Islam, the effects of Islam on social stratification, and the elements of "reliability", "respect" and the "place" of social classes are considered. The results of the study show that the introduction of Islam to Iran led to new social norms and values, and changed the political and social systems. As a result the place of some of the social classes (upper and middle) was changed, but the continuation of the economic structure led to the stabilization of a part of the low class people.