Because of the changes through the time, language in the past varies greatly from it in the present day. This difference especially can be discovered in semantic system. Scholars, by applying various kinds of approaches and concepts to the research of Ancient Chinese language, aims to comprehend the usage of Chinese phrase more precisely. By using the theme of this conference -- Hai yang (ocean), I will first settle the original meaning of Hai and Yang, taking advantage of their same sememe --the shared characteristic of containing water to discuss the meaning of the related phrase, Cheng Pian Shui Yu (water region). Next, I will start from the combination of disyllable words in Chinese and its characteristic in structure to discuss how these two words, Hai and Yang, are used separately and combinatively in ancient texts, when this phenomenon begins and how their structure and semantics meaning change. The research of the semantic relation in phrases is contributive to grasp the precise analysis of their meanings and realize the development and evolution of the system. Hence, I use semantic component to highlight the difference between these related terms with the same sememe and cut the traditional lexeme into smaller components of meaning to better comprehend the evolution of semantic system. The semantic field provides the ground of the study in semantic system. How these two words, Hai and Yang are closely associated in Modern Chinese demonstrates the close relation of their meanings. Because of their universal meaning, these words are combined into the disyllable compound word in Modern Chinese. This paper intends to study the disyllable compound word in Chinese diachronically to observe the trajectory of its development, to compare these changes synchronically to analyze the structural characteristics, and to further discuss the reason why they transform.