The second half of the third Hijri century, coinciding with the reign of three caliphs, al-Mu’tamid (256-79 AH), al-Mu’tadhid (279-89 AH), and al-Muktafi (289-95 AH), Abbasids restored their authority and renewed their organization. This reform process which was began by Abu Ahmad al-Muwaffaq (d. 278 AH) and reached its climax at the time of Abu al-Abbas al-Mu’tadhid stood between two decline periods: the first one is known as the period of Samarra, when the Turkish and non-Turkish slave soldiers assumed the reign of the caliphate, and the second one which started with the reign of al-Muqtadir (295-320 AH), witnessed the corruption of the court, the collapse of bureaucracy, and the destruction of the military organization and ended by the Buwayhids entrance in Baghdad in 334 AH. The created structure had several features: concentration of power in the caliphate, concentration of bureaucracy and its supremacy to military force, prevention of land granting in return to administrative or military services, and lastly, development of a permanent wage-earner army. The administrative procedures of these reforms are going to be studied in present paper, with an emphasis on transformation on military construct.