Abstract: During the period of the Republic of China, with the social fission and the understanding of the Western sea power theory, Chinese researchers gradually changed from local officials to emerging intellectuals, who gradually focused the discussion on the three themes of sovereignty, modernization and the change of nationality. On the issue of sovereignty, according to the characteristics of Western sea power invasion, they put forward a coastal defense strategy of maintaining territory and developing sea power. On the issue of modernization, they put forward the ideas of “Using sea power to strengthen national strength” and “Building a new country through overseas trade”, trying to introduce China into the global marine trade system in an all-round way and building a modern country based on overseas trade. On the issue of nationality, they proposed to take the residents of the southeast coast as the leaders, let them drive China’s transformation to a marine society, and to improve the awareness of the whole nation in terms of sea power. During the period of the Republic of China, scholars’ discussion of sea power was intertwined with the relationship between learning external knowledge and resisting western invasion, the relationship between tradition and modernity, and the relationship between achievements and morality. These studies not only reflect the intellectuals’ expectation of China becoming a powerful country, but also inspire the people, and also reflect the deficiency and lack of their thoughts under the limitations of the times and identity.