This article explores the Cøllø political structure and Institution in South Sudan from 1545 to the present day. Politically, the Cøllø state was divided into a number of multi-clan settlements. In each of these settlements, there was a dominant lineage around which other descent groups gathered to constitute a settlement. The study aims to investigating the autocratic government of the Cøllø Reth (The Shilluk King). This system was laid down by Nyikango Okwaa at that time around 1545 and still continues by his successors. The laid down system of marriage of the Cøllø girl is still now ten cows, which had not been altered by the succeeding kings. The Cøllø political system is unique than other tribes because it is centralized system. This system is laid by the king and the chiefs appointed by the king.

Keywords: South Sudan, Cøllø Rathdom, Political structure and Institution, Autocratic government, Cøllø political sphere.