The convergence of ethnic-religious groups is a different issue in the field of strengthening relations between countries. The Islamic Republic of Iran and the Republic of Iraq are two countries that have a significant population of Shiites in the world. In Iran, Shiites have succeeded in building a system, and in Iraq, since 2003, they have played an important role in the structure of the Iraqi system. Since Shiites and Shiite ideology play an influential role in the two political systems, understanding the factors of convergence and divergence is an issue worthy of attention in the relations between the two societies. Using descriptive and analytical methods, using Delphi and AHP methods while using library data and field findings, this article seeks to answer the question of what factors cause the convergence and divergence of Shiites in Iran and Iraq. The findings show that the common culture based on Shiite beliefs, including the issue of honoring the Supremes, in addition to major political interests, such as the importance of maintaining the power of Shiite parties and currents in the political and economic structure of Iraq, such as trade, the reconstruction of Iraq, and crystallized security in dealing with the common threats of factors They are considered to be the main convergence of the Shiites of Iran and Iraq. In contrast, factors such as the internal equations of the two countries, including the internal rivalries of the Shiite parties in Iraq and the existence of Western and Eastern trends in Iran, as well as the influence of foreign actors, are considered the main factors of the divergence of the Shiites of Iran and Iraq. Although in the current situation, the weight of convergent factors is more than divergent factors, this superiority is fragile and can lead to divergence.