Isis as a new demonstration of radical Islamic fundamentalism, has committed many crimes in Iraq and Syria under pretext of restoring the Islamic Caliphate and as an effective actor in politics and international relations it has played an increasing role in the current international arena. Therefore, the question is that could the various theories of international relations to explain the motives, objectives, procedures and behavior of this terrorist group?Religious extremist group behaviors are not based on rational actor model that can be easily understood or managed. On the other hand, their behavioral rules are not in accordance with the most basic assumptions of the international relations theories, so neither the mainstream nor mid-stream do not have possibility of comprehensive analysis. However, there are concepts of constructivist analytical framework which have a view to sociological, normative, identity, culture factors and emphasis on the role of discourse that provide a more appropriate context for the analysis of identity- ideological groups, Including to consider principles of collective identity and ontological security in addition to physical security which are more able in analyzing the behavior of Isis in the field of international.