This paper aims to develop an index to analyze regional cooperation in Northeast Asia, which is Northeast Asia Regional Cooperation Index(NARCI). NARCI evaluates intra-regional cooperation and integration in four areas, which are functional cooperation, politico-security cooperation, socio-cultural cooperation, and institutionalization, in order to identify the conflict and cooperation situation in the Northeast Asian region. The analysis of economic integration found that Northeast Asian regional cooperation is characterized by a high level of integration in goods trade and regional value chain cooperation, but a relatively low level of integration in intra-regional direct investment and energy supply chain cooperation. The analysis of the political and security cooperation shows that the intensification of U.S.-China competition and the factional confrontation between Korea, U.S., Japan, and North Korea, China, Russia have had a significant impact on regional cooperation in political and diplomatic security. The result shows that the level of integration is low, with all evaluation indicators being negative. The analysis of the socio-cultural integration shows a relatively low level of integration in civil society cooperation and intergovernmental exchanges, a relatively high level of integration in cultural and educational exchanges and study abroad, and a neutral level of integration in information technology cooperation, labor mobility, and the share of tourists in the region. Finally, the analysis of institutional integration shows a relatively high level of integration in the bilateral channels between governments and the institutionalization of regional cooperation in the socio-cultural field, and half of the countries had institutional integration in financial integration and regional cooperation in the economic field. The level of integration in the political and security field was low due to the existence of only multilateral meetings. The analysis of NARCI shows that the impact of geopolitical conflicts on the economy and socio-culture has been expanding in recent years. However, the low level of political and diplomatic cooperation in the region and related institutional deficiencies are considered to be insufficient to buffer these risks, and efforts are needed to address them.