This paper attempts to, address two major questions: Why did the structure of State in Pahlavi period become different from that of Ghajar? Which Structural Factors can account for the modification of the state. Structure from a traditional to a modem form? To do so, based on the literature of modem state, an ideal type of modem state was developed and its components were identified. Following a structural approach, the emergence of the modem state is explained by the integration of Iran into the world system in the Ghajar era. It is argued that the failure of Ghajar state to adjust with the world system requirements resulted in Misroute (Constitutional) revolution. However, due to the weakness of Mashroteh State in the establishment of a modernized state structure, the country experienced anarchy and chaos. This situation prepared the ground for the rise of Reza Shah and the Seize of power enjoying the support of Britain, the main power in the world system then. The new state adopted policies to modernize the State Structure. These policies resulted in the increase of state power, marginalization of local powers and other sources of authority, the development of state supremacy, the improvement of social relations of different segments of society, the integration of ranian society and its unification into a National identity. These polices paved the way for the transformation of the state structure and the emergence of an authoritative modem state for which the social conditions of Iranian society were also in line with.