The purpose of this study is to help comprehension of internet online social network service that are becoming the latest topic and to analyze controversial points that can happen in overseas internet enterprises by examining the global strategy of SK communications ‘Cyworld’. Online social network service industry has the characteristic that technology and culture are mixed, which means platform standardization strategy and highly localized strategy are required at the same time. Therefore, online social network service has a lot of difficulties in coordination of integration and responsiveness than any other industry. Although SK communications ‘Cyworld’ is domestic market leader, they also faced difficulties in security and diffusion of customer base in foreign markets such as China, Japan and the United States. Through this case we can offer implications on decision making process and implementation of global strategy to domestic internet enterprises which are going to enter global markets.