In this article, I have considered the background, characteristics, content and meaning of tone organization theory achieved by Dr. Uncho Jang Sa-Hoon in the development of Korean musicology. Uncho explained the characteristics and transitions of musical tones by illuminating the scale and method of traditional music based on various old scores and documents, and paying attention to the characteristics of melodies and performance techniques such as vibrating tone(搖聲) and sliding tone(退聲). The themes that Uncho studied as the most characteristic and important performance techniques in Korean traditional music were vibrating tone(搖聲) and sliding tone(退聲), which have now been established as important concepts and terms in the theory of tonal organization in Korean music. It is a brilliant achievement that only Uncho could achieve by applying the transcription and analysis of current music and oral music to the scale and tonal organization theory derived from literature research. The study of the tonal organization of Uncho's traditional music began with reflection on the existing theory and was followed by research through Geomungo performance method, and was extended to classical songs(Gagok, Gasa, Sijo), folk songs, Sanjo, and Pansori. It was considered meaningful in that both historical approaches and analytical studies were combined, and that classical music(正樂) and folk music were uniformly recognized, and that the tonal organizaton theory of Korean traditional music was created. The significance of Uncho's tone organization theory is that it is a form that combines the performance characteristics with the music mode, and intends to contain all the characteristics of music in one small unit called scale. It was a result derived from the Korean tonal organization theory, and it is meaningful to establish an integrated theory that encompasses all branches of Korean music. In a word, Uncho theory became the mother of Korean music tonal organization theory. In particular, it is considered to have influenced the formation of Lee Bo-hyeong's Tori theory and Oh Yong-rok's dynamic scale theory. However, in the operation and analysis of mode(樂調), it was common in the Uncho generation, but now there is room for looking at it from a different point of view. I hope that active discussions on the important issues raised by Uncho will continue in the future.