After the Islamic Revolution, the foreign relations of the Islamic Republic of Iran underwent a fundamental change, which can be observed in the formation of new boundaries in international relations different from Iran’s foreign relations during the Pahlavi era. What is noteworthy is the different type of foreign relations in the different periods of the political system of the Islamic Republic of Iran, including the second period, characterized by the idealist ideology-centric rule, and the third period, characterized by the pragmatic rule. The fundamental question arises as to what factors have been influential in shaping the different foreign relations of the Islamic Republic of Iran in these two periods. The findings of this research are based on the proposition that the influential factors in shaping the different foreign relations of the second and third periods include the different weight and significance of four key variables: the structure of the international system, domestic needs, the attitudes of decision-making elites, and geopolitics in defining national roles and goals. In fact, the different weight and significance of these four fundamental variables have led to the definition of different national roles and goals in the second and third periods, and as a result, have directed and ultimately led to the different foreign relations of these two periods. The research method in this study is descriptive-analytical, and the data collection method includes library, documentary, and online sources.