Abstract: Many companies are faced with diversified strategic choices, especially for the companies in tourism industry which have innate tendency of diversification due to the high risk market. Taking the listed companies in China's tourism industry from 2005 to 2013 as samples, this article tries to analyze the correlation and causality between the social network at different levels and the corporate diversified strategies by comprehensively using the methods of quantitative multiple linear regression and qualitative comparative study, and a robust and consistent conclusion comes out in the end. The corporate social network may help enterprises reduce trade costs in gaining access to external resources, thus reducing the motivation of enterprises to internalizing the external resources through diversification; individual social network will help the management to gain knowledge and information of new products and markets, so as to improve their capability for diversification. Meanwhile, in the uncertain market environment, the corporate social network can help enterprises to control their transaction costs more effectively, so as to further reduce their motivation for diversification.

Key words: individual social network, corporate social network, diversification, environment dynamism