In the scripture of Daesoon Jinrihoe, the expression 'Dosu (度數)' is frequently used and Jeungsan, Jeongsan, and Wudang also left behind many teachings related to Dosu. In this paper, the concept of Dosu is analyzed in detail and the achievement of an in-depth understanding of the concept of Dosu is attempted. The term Dosu is often used in traditional literature. In the classics, Dosu was used to mean institutions, standards, rules, law, figures, and the laws of heavenly bodies. In other words, Dosu is used to mean the laws of astronomy and the norms of human society. This meaning is expanded and used as the principle of the universe and nature. This concept of Dosu is related to the mathematical cosmological understanding of numbers as the principle of the universe. This type of mathematical cosmology was systematized by Shao Yong (邵雍). In the Joseon Dynasty, Seo Gyungduk (徐敬德) accepted it positively, and it thereby became an influential trend in Korean thought. In the world view of Daesoon thought, there exists the view that numbers as a principle of the universe, and of course this world view is connected to mathematical cosmology. In Daesoon thought, the concept of Dosu is based on the concept of traditional Dosu and adds an additional meaning which connects it to the Reordering of the Universe (Cheonjigongsa). Also, Dosu is used to mean the process of changing the principles and laws of cosmos through Jeungsan's Reordering of the Universe. It is especially the case that discourse about Dosu is widely used when describing the Reordering of the Universe. Jeungsan corrected, reorganized, and adjusted Dosu, as well as establishing new Dosu. Jeongsan, who succeeded Jeungsan, followed the Reordering of the Universe by Jeungsan, and also realized Dosu. In other words, Jeongsan acted and practiced according to the Dosu that had been enacted by Jeungsan. Also, Dosu means the process of the transformation of principle according to the Reordering of the Universe, and Wudang used the concept of Dosu to describe the historical process of Daesoon Jinrihoe. This means that the foundation of Mugeukdo, the change to Taegukdo, the establishment of Daesoon Jinrihoe, and the contruction of Yeoju headquarters are episodes in a divine history carried out through Dosu. Through this discourse, Daesoon Jinrihoe asserts a legitimacy that distinguishes itself from other sects, and believers can be inspired by the sacred meaning that they are participating in the Dosu of heaven and earth. This empowers their devotion and sincerity.