The exploration and construction of marine culture theory system have been constructed for years，but as a specialized theoretical system，it has not been recognized by the academic community. As a report on marine culture of China，it is necessary to discuss the subject dilemma and breakthrough of marine culture in 2020. Whether marine culture is a subject or a field，a collection of knowledge or a theoretical system，is still controversial in the academic community. The subjective construction of marine culture subject is confronted with the inertia challenge of traditional academic thinking，the challenge of putting what is learned into practice thought，the challenge of fuzzy category of research object and the challenge of lack of self-integrated research method. How to face the challenges，get out of the dilemma of theoretical construction，realize the breakthrough of theoretical subjectivity，this paper consider the study should adhere to the theoretical construction of the subject of the oceanic people，adhere to the value orientation of harmony in the oceanic people，adhere to the research category of the oceanic people. In this way，it can be gradually established and solidified the subjectivity of marine culture as a discipline system，make the marine culture research become the soft power that promotes “Chinese Dream”，and become the ideological basis，theoretical consciousness and action direction of building a powerful ocean country.