Iraq socially textured mosaic of ethnic groups in numerous sectarian. Three demographic and Political nature of the country always has potential areas of tension and separation. America and its allies attack and the fall of Saddam's regime, released the fundamental forces in the north and south of Iraq, who were repressed for many years and provide them an opportunity to gain a greater share of power in Baghdad's government. Shia ‘a, Sunni and Kurdish are three main ethno-sectarian groups with different interests in Iraq. What matters over the role of the Shia’s in the process of state-building in Iraq is that the Shi’a in the past decades due to various reasons was out of power. The fall of Saddam's government caused that the role of Shia’s authority role as an active political force and actor, being increasingly discussed.This study sought to examine the role of the Shia’s authority in Iraq's state-building process with an emphasis on strengthening the rule of Shia’s Ayatollah Sistani’s thought. According to the structures of ethnic, tribal and religious in today's Iraq policy, it seems that legal and political positions of today authority about the role of supervision, guidance and actors in the political system, has an important influence on political and social developments and state-building process by strengthening Shia’s rule in today Iraq.