This article was writting by Ts.Shagdarsureng under the aegis of Korea Foundation, in the Department of Mongolian Studies of the Dankook University, Korea, in 1996. Without doubt, in the world linguistics field, the Korean language belongs to Altaic language family, which also include Turkic, Mongolian and ManchuTungus. Among the studies on the origin of Korean alphabetical script Humin jongum (HJ) of 1444, the attention of scholars from many countries, such as Korea, China, Japan, Russia, USA and Mongolia, is rnncentrated on the relation between Korean and Mongolian scripts. But the opinions regarding the origin of HJ can be devided in two groups: first, HJ is devised on the Mongolian `Phags-pa script, second, HJ is created on the basis of Mongolian script. At the present stage of the author s opinion, this all studies are based on the outward or external similarity of afore-mentioned three scripts. So, in author`s opinion, although external similarity are interesting, the internal systematical similarity is more important for the comparative paleography. The author of this article draws some following conclussions: 1. In the period of King Sejong (1397-1450), the Korean linguists have laid the foundations for a new phonematical principles, corresponding to the agglutinative nature of the Korean language, non-similar to the traditional phonematical basis of Chinese origin. This new phonematical principles served as theoretical basis of HJ. 2. In the comparison with Mongolian writting systems (Kitan, Mongolian and`Phags-pa scripts), HJ have following similarities: 2. A. In the field of the structure of characters of HJ: - The graphemical composition of the vowels HJ and Mongolian script; - The function of korean i-yong and mongolian aleph in the initial position of vowels; - Two forms or initial and medial-final forms of the vowels of HJ and `Phags-pa script; - The $quot;Symbolisation$quot; of the organs of speech of consonnes of HJ and the explanation of the rnnsonnes on the partiapation of the organs of speech in the Mongolian script. 2. B. In the field of the creatation of syllables or words in HJ: - The prinaples of the $quot;group form` in the creatation of syllables of HJ and Kitan script. In final, the author advanced a new hypothesis about the influence of HJ on the Mongolian horizontal-squre script of 1686 by Jana-bajra.