Most of the existing research Focus on the affection of social capital to the national identity. The main concerns of these studies are due to the promotion of social cohesion. However social capital variables do not only serve as a result of national identity. According to the claims of Putnam(1993) and Uslaner(2002), social capital and national identity have a mutual influence relationship. Vertical / horizontal social capital and the ethnic / civic identity are very similar in terms of the closed / open properties. In this perspective, this study aims to examine the relationship of social capital and national identity. This study's starting point is that Social cohesion can be more enhanced. through a combination of social capital and national identity. In addition, unlike previous Western-oriented studies, this study aims to analysis of the characterization by ethnic diversity between the eastern and western countries. Based on the World Value Survey data from 2005 to 2008, this research finds following results. ① The Levels of social capital in Eastern and Western countries are significantly different. Korea and China have the high vertical social capital (private trust), while the america have high horizontal social capital (norms, general trust, participation). However, the government trust appear differently depending on the political regime. China's socialist system is higher than the capitalist system of Korea and the United States. ② Cross country differences in the level of national identity are also very large. America is the highest and korea is the lowest. In addition, the america' difference of ethnic / civic identity is very obvious than that of Korea and China. ③ Social capital and national identity in all countries show causality. Ethnic identity and vertical social capital has a positive causality and horizontal social capital and civic identity has a positive causality. ④ In the variables influence of Social capital and national identity, there is a significant cross-country differences. Korea's national identity has a positive causal relationship with personal trust, China's national identity has a positive causal relationship with government trust. On the other hand, America's national identity has a high causality with all the variables of the social capital. From these results, this paper discusses research implications for further research.