Japan’s theory of the “maritime nation” has been shifted from the academic discourse to the social discourse widely shared by the intellectuals，the media and political circles. The discursive structure of “maritime nation” in Japan has mainly links with the issues of Sino-Japanese relations，including “Japan being threatened by China on the sea” and “Japan keeping guard on channel security”. It is also connected with the “freedom and democracy” which derives from the Cold War mentality and its historical origin. Japan’s discursive construction of “maritime nation” is characterized with the rise of “nationalism” and has got the social conditions in terms of its subject，object，content and platform，aiming at making sense of urgency by exaggerating “the China’s threat” on the sea and seeking the solution by relying on the Japan-U.S alliance in dealing with the issues of South China Sea and East China Sea. It is necessary for China to see the essence of Sino-Japanese relations through Japan’s superficial discourse of the “maritime nation”，and work to improve China’s capability in the international competition of discourse power，on the basis of understanding the transformation of Sino-Japanese relations in the new context of globalization.