The purpose of this paper is for studying of the function and meaning of postposition ‘beuteo’(브터) focusing on the diachronic change of ‘beuteo’. Also, for grammatical characteristics of ‘beuteo’, we tried to understand its meaning and researched on how it was recognized by comparing ‘beuteo’ and its Chinese translation in Korean annotation of Chinese literature of middle age Korean. As a result, we found that ‘NP-eulbeuteo’(NP브터), ‘NP-robeuteo’(NP로브터), ‘NP-beuteo’(NP브터) in Korean annotation of Chinese literature appeared differently depending on whether corresponding Chinese were recognized as lexical morpheme or grammatical morpheme. In other words, ‘beuteo’, a conjugation of ‘beut-’ and postposition ‘beuteo’ co-existed in middle age Korean, and it is appropriate to exclude ‘beuteo’ combined with relationship-indicating postpositions ‘eul/reul(/)’ from the grammaticalization process of postposition ‘beuteo’ since it is a conjugated form of predicate that differs from grammaticalization of postposition ‘beuteo’. Also, I realized that ‘NP-lobeuteo’ can be understood in its relationship with ‘NP-rosyeo’(NP로셔), and I set the grammaticalization process of postposition ‘beuteo’ by reviewing their correlation. Furthermore, by focusing on the usage of Chinese preposition appeared in original Chinese document, I studied the corresponding relationship between Chinese preposition and Korean language, and based on this study, I summarized the meaning and function of ‘beuteo’, a middle age Korean postposition.