The emergence of the Seljuq dynasty is one of the great events in the history of Islam and marks the beginning of a new period in the history of Shiism. According to the ups and downs of Shiism in the Seljuk period, the performance of this government towards Shiism can be divided into two periods: a) The first Seljuk period (429-483 AH) due to their interest in supporting the Sunnah and the power of the rulers. The early (Tughrel, Aleb Arslan and Malek Shah) Shiites faced the harshness of the new rulers. The strictness of Nizam al-Mulk, the most important minister of the Seljuk government, towards the Shia sect, especially the Nizari Ismailis, is well known. b) The second period of the Seljuq government (483-590 AH) In this period, Shiites were able to become suitable administrative officials, especially as Seljuq court officials, they also achieved the highest positions. During the period of the Khwarazmshahs, Sultan Mohammad Khwarazmshah, who considered the most important basis of his legitimacy to be military power and warfare, tried to legitimize some religious jurists. But in the end, following a dispute with the Caliph and in a conflict with the Mongols, he lost his government and power and caused new developments that had heavy effects and consequences on Iran and the Islamic world. In this article, we intend to answer these hypotheses with analytical-descriptive method that: the tendency of some Iranian sultans towards the appearance of Shiism, with the aim of attracting Iranians, has contributed to the cultural attraction of Shiism, and the results of the research indicate that Although the study of historical sources reports the suppression of Shiites by some Seljuk sultans in some parts of the late Seljuk period, in general, the influence and expansion of Shiism in many areas of Iran and even Baghdad, especially in the caliphate system, finally The improvement of the position of the Shias increased and gradually raised them as a reliable force in the political balance, and the examination of the performance of the Khwarazmshahs with the Shias also shows that the Khwarazmshahs did not pay attention to the Alawites and whenever the interests of the government They demanded action against them. The sultans of Khwarazmshah were aware of the growing Shiite movement at this time, and both of them tried to take advantage of this growing movement to destroy the rival, and therefore none of them had followed the Shiite religion.