Abstract: With economic diplomacy as the main means, Japan values and actively promotes all-round diplomacy in Southeast Asia. Yoshihide Suga selected Vietnam and Indonesia for his diplomatic debut in less than a month after he formed his cabinet, making it clearer the trend of Japans emphasis on ASEAN diplomacy and exerting influence on ASEAN through Vietnam, Indonesia and other key countries since Abes second cabinet. Vietnam holds the 2020 ASEAN presidency and is also a non-permanent member of the UN Security Council that year. Vietnam hopes to establish a regional and even international image through its coordination role within ASEAN and between ASEAN and relevant countries in the region. Vietnam, which is implementing a policy of “renovation and opening up”, has high hopes for Japans capital, technology, and market, and has also made it clear that Vietnam welcomes Japans role in the field of security. Japan is looking for opportunities to get involved in the economic, political, and security fields to help Vietnams economic and social development while containing Chinas growing influence in the region.The successful signing of RCEP at the end of 2020 will bring new opportunities for East Asian cooperation, and East Asian economic cooperation will be further deepened.With ASEAN as the core, it is an inevitable trend to promote multilateral regional economic cooperation among China, Japan, ASEAN, and the Mekong Sub-region countries, and to push forward Japan-Vietnam, China-Vietnam, and China-Japan bilateral regional economic cooperation.

Key words: East Asian regional economic cooperation, Japan-Vietnam relations, Japan-ASEAN relations, presidency, summit diplomacy