Guweon, Deokgyu(권덕규, 1890~1950), as a disciple of Ju Sigyeong(주시경), and as a scholar, had protected Korean, and the language itself before and after the colonial period. To organize the statement stated out in this writing is as follows. First, Guwaeon Deokgyu birth and thoughts are in indivisible relationship with Ju, Sigyeong. Especially after death of Ju, instead of Kim, Dubong(김두봉) who became a refuge in ShangHai and Choi, Hyeonbae(최현배) who was studying in Japan abroad, he recreated "JOSEONEO YEONGUHOI(조선어연구 회, Association for Research on Korean Language)" domestically and led Korean research. This achievement was not only for love of his teacher but also for the love of Korean literature itself. Second, Guweon`s korean research method stated by "Necessities of Choseon Language(Korean) research" are regulated by "practicality" , "scientific", and "applying methods". Considering all these aspects, we can find out that his Korean research is on the basis of not only on practical way but also in scientific way to advance possibilities of applying. Third, we have divided Guweon`s Korean research into "Language and Korean Language theory", "Marking of the phoneme", "Research of vocabulary, Language origins and consideration". His Korean literature research has the basis of linguistic nationalism, which was created after death of Ju Sigyeong, and has close relationship with process of Korean literature`s law(standardization).