Khajeh Nizam al-Mulk Tusi, the famous minister of the Seljuk era, served as ministers of two kings of the dynasty, namely Alb Arslan (1067-1077) and Malik-Shah (1077-1097) for thirty years and played the main role in organizing and managing the Seljuk government. One of his most important measures was creating an army referred to as the Nizamiyeh slaves. This organized group, consisting of slaves bought by Nizam al-Mulk, operated directly under the command of the minister. Particularly after the death of Nizam al-Mulk, they were one of the most influential groups in the political events of the Seljuk era for about a decade. This research tried to answer the question of the purpose and motivation of Khajeh Nizam al-Mulk in creating a group of military slaves as well as the role they played in the political currents of the Seljuk era, using a descriptive-analytical method and utilizing first-hand sources of that time. The findings of the study indicate that the insecurity in the position of bureaucrats in the pre-Seljuk dynasty, i.e. the Ghaznavids, and in the Seljuk era urged Nizam al-Mulk to establish an independent military force to stabilize his position as a powerful bureaucrat. This group also appeared influential in the political currents of the Seljuk era after Khajeh's death.