This paper is a review study on Dr. Lee Hye-ku’s “Changes of Tai-sung ak under gone during Koryeo Dynasty”(1965). In the article of Koryeosa ‘The date of 6th in February 18, King Myeongjong(1188), in addition to the main text, an unknown critique(史論) is attached. Dr. Lee Hye-ku interpreted the contents as facts from 1188, and presented the stage of the transition of Daesung-ak in three stages. In this paper, we estimate the time of writing and the author of the critique, and examine the contents in detail, and explain why it is difficult to view the 18th year of King Myeongjong as a major transition stage. The time of writing was estimated at the time of King Gojong, the time of compilation of The Annals of Myeongjong. The authors presented it with two people. It is Kwon Jung-gyeong, one who was a writer of the Myeongjong Annals, and Lee Gyu-bo, who wrote a poem about the Taemyo ritual in the 2nd year of King Gojong(1215). The content of the critique is largely understood as ① historical facts, ② records of the Taesang departments (太常府) cited while writing, and ③ the writer’s perspective on the A-ak(雅樂) tradition. The historical fact is that there was a change in the dance of the ritual in the 15th year of Uijong(1215). There was a change in the number of dancers (36 members → 48 members) in the first, second, props(Shield and arrow → Shield and ax), and music and dance(Original A-ak → A mix of Korean style music and dance). The records of Taesang-Pyeonje (太常編制) he cited reflect the positions and views of the musicians at that time on change. The point of view in the quotation is clearly difficult to know. What is most noticed is the writer’s point of view. He questioned the legitimacy, saying that “Daesung A-ak” was not produced by Emperor Song Taejo, and that the country was in crisis after the music was enacted. And he questioned the legitimacy of ‘Daesung A-ak’ because it was not produced by Emperor Song Tae-Jo of China and that the dynasty fell into crisis after the establishment of this music, and criticized the change from rituals after the Uijong period(1146-1170) to a mixed form of Hyangak(鄕樂), not exclusively for A-ak. Summarizing the above, this paper discusses the reasons why the content of the article written in 1117 should be interpreted as an article reflecting the author’s opinion of the time when the Myeongjong Annals(1227) were compiled and the author’s opinions, rather than recording the history of 1117. And on the basis of this, instead of seeing the changes in Koryeo A-ak as three stages during the times of Yejong, Uijong, and Myeongjong, it was reasonable to see them in two stages during the times of Yejong and Uijong. Therefore, A-ak in the Koryeo Dynasty underwent two phases of change : the period when Daesung A-ak was accepted in 1116 and operated as a ‘Aak-only’ and in 1611, a period of ‘Hyangak-combined use’, which attempted to cultivate Hyangak in A-Jong-heon(亞․終 獻) in ritual ceremonies. It can be said that was passed down to Joseon after the end of Koryeo. In the Confucian ritual procedure, the fact that A-ak was not converted and used as a combination of Hyangak was generally judged as ‘destruction of A-ak’ or ‘incompleteness’. However, this is I think other evaluations are possible if we look at the point of view that A-ak has been Koreanized.