The history of the Pahlavi era is the transition period of Iran from the semi-colonial era to the neo-colonial era and dependence on the imperialist powers. The present research has studied Iran's foreign relations in the first Pahlavi period based on the theory of "dependency". In the circle of competition between the two top powers of that period (that is, Russia and England), Reza Shah practically turned into a dependent agent and lacked will. In the framework of this competition, he was the executor of the policies of the colonialists who sought their interests in the dependence of the Iranian government on them. Based on the "dependency" method, the current research has sought to examine the main problem of the research, i.e. the functioning of Iran's foreign relations during the first Pahlavi era. Based on the findings of this research, Reza Shah's love and fascination for Western culture and civilization led him to blindly imitate Western culture and try to implement that incongruous culture in the Islamic society of Iran. At the same time, his fear and concern about the western conspiracy against his government, made him to obey the foreigners more, which trapped Iran in the complex circuit of dependence in various dimensions.