Under the theoretical framework of entrepreneurial event theory, the paper conducted a questionnaire survey through the entrepreneurs in Guangdong, Zhejiang and Hubei. Based on the survey, this research focused on the affective mechanism of perceived desirability, perceived feasibility and the interaction effects on the formation of entrepreneurial behavior. And the research also investigated the moderating effect of social network building capacity in the above process. The results indicated that the perceived feasibility played a significant role on the formation of entrepreneurial behavior but the perceived desirability did not. However, under the moderating effect of social network building capacity, perceived desirability and perceived feasibility had an interactive mechanism: in the situation with low perceived desirability (perceived feasibility), perceived feasibility (perceived desirability) had a more significant influence for individual entrepreneurial behavior.