〈Haedongakbu〉 of Yu-Won Lee is included in the two books, “Imhapilki” and “Gaogoryak.” However, there is difference in the number of works between the two books. The 121 works of “Imhapilki” consist of the 100 works of Haedongakbu of “Gaogoryak”, the 16 works of Bojesanak, and the 5 works of Hunminjeongeum. Comparison the introductions of ‘Haedongakbu’ of “Imhapilki” and “Gaogaryak” showed that Yu-Won Lee wanted to organize the history of music of Haedong. He thought that they can be classified under the single category, ‘Haedongakbu’ although the three groups of works are different each other in terms of the period and order of creation, and he implemented his thought. Therefore, the number of works of 〈Haedongakbu〉 of Yu-Won Lee should be 121. The existing ‘Haedongakbu’ was mainly created to describe real events in history. Therefore, the Haedongakbu mainly included historic events, and evaluations about them. However, 〈Haedongakbu〉 of Yu-Won Lee focused on music history. Our 3,000 years music history was organized under the name of 〈Haedongakbu〉 thanks to the effort of Yu-Won Lee. He used four different techniques in order to describe the flow of music history, and they were historical truth, selection, compression, and transformation. Yu-Won Lee, firstly, verified the historical truth on the works by studying domestic and Chinese documents like “Jeungbomunheonbigo”, “Haedongyeoksa”, and “Donguktonggam” and investigating the mentions of senior scholars. He collected resources that were necessary for the establishment of music history. Secondly, he selected only the necessary resources because the data of 3,000 years tradition was too vast. He selected works that are in line with Confucianism and help to enlighten people. Thirdly, Yu-Won Lee used the technique of compression for simplification if the works had lots of historic records. A work was comprised of a title, an akbusi, and an epilogue, and he simplified all these elements in order to clarify the content of the work. Forth, he used the technique of transformation in order to establish music history. Especially, he changed the contents of music if the music had the contents disadvantage to us. It was a way of showing the tradition and superiority of our music.