The motivation of Japan’s institutional discourse right in the RCEP negotiations is closely related to its comprehensive diplomatic strategic planning and touches different aspects；such as economy，politics，and diplomacy. The path includes the right of discourse on rules and the right of relational discourse. The former highlights the measures taken to establish rules and regulations，while the latter focuses on promoting relations with India and ASEAN countries. Japan’s action to enhance the institutional discourse right in the RCEP negotiations has achieved certain results，which has helped it enhance its international influence and build a regional economic and trade order in line with Japan’s interests. However，at the same time，Japan has also made a series of concessions，reflecting the limit of building the institutional discourse right. The validity of Japan’s institutional discourse right in the RCEP negotiations has a certain enlightenment and reference role in thinking about and enhancing China’s institutional discourse right in the international economic and trade order.