This study amis at grasping Toegye Yi Hwang(1501~1570)`s concept of li理 through his analysis of the Chinese character lidao理到.\nZhu Xi(1130~1200) annotated The Great Learning大學`s concept Wuge物格, the result of Gewu格物(Investigation of things), as “物理之極處, 無不到也”. The expression lidao理到 is the abbreviation of Zhu Xi`s annotation of Wuge. The academia in the sixteenth century Korea, there was a problem about how to insert a suitable gugyeol口訣(Korean postposition) between “物理之極處” and “無不到也”. Some thinks that it is correct to insert subjective gugyeol ‘이/가’. Following this view, lidao can be resolved into subject li理 and predicate dao到. The other perspective is that locative case gugyeol ‘에’ is suitable. Following this view, lidao can be resolved into adverb li and predicate dao, and translated as “I arrived at li”. At the first time, Toegye understood lidao as “the unmovable metaphysical principle personally arrived to mind”, and took a negative stand on this view.\nSubsequently, Gobong Ki Daeseung(1527~1572) provided several interpretations for Toegye. Using such examples, Gobong argued the word lidao can be translated as the structure of subject-predicates, and Togye finally accepted Gobong`s point. The basic definition of Chinese character dao到 is laidao來到 , which is mainly interpreted as to arrive . In the context, however, dao is also understood as zhoudao周到 or daojin到盡 , mainly interpreted as to understand thoroughly . Gobong`s examples illustrate a different usage of dao. In this view, appropriate interpretation of lidao is “Li was completely understood.” The scholars of Toegye School in seventeenth century also interpreted Toegye`s changed view of lidao as “Li was ultimately understood.” Translating lidao, Gobong and Toegye School`s scholars just focused on the interpretation. However, Toegye applied the tiyong體用(substance and function) structure of li理. He understood that the yong用 of wu物(the thing)`s li, the operation of li, can accord with mind after investigation of thing`s li, and these condition can be called as “The wu`s li personally arrived to mind.” Ti體 of wu`s li, the unmovable metaphysical substance itself, however, actually dose not escape from things. Toegye`s agreement of lidao means that he agreed with a kind of activity of li in aspect of li`s yong through interpretation of wuge. Moreover, his interpretation of lidao is applied metaphysical way to understanding Confucian epistemological concept gewu格物 which was mainly understood as epistemology in physical side.