The concept of "Regime" is one of the most widely used concepts not only in international relations, but in economics, law, environment and more. In this study, we have examined three different approaches in the definition of regimes, "behavioral", "knowledge" and "formal", and to scrutinize the definition of Regimes that have presented by Scholars Such as Krasner, Young, Kratochwil & Ruggie, Keohane, and Osherenko & Young. It also examines the major intellectual approaches in the study of international regimes will be discussed. Then to review the main dimensions used in the study of Regimes, "the regime formation", "the regime strength," "the regime effectiveness," "the Scope of the regime" "the regime robustness (resilience)", "organizational form" and "Allocational mode". Then, provided the Levy, Young and Zurn’s Categorization of regimes. it is concluded that Islamic Republic of Iran has formed  a tacit informal regional security regime in the Middle East, and In Final to scrutinize the various aspects of the regime, including principles, the norms, rules and decision-making procedures.