Based on Nahapiet & Ghoshal’s (1998) three dimension social capital framework, this study develops an interactive mechanism model between employees’ continual use of the intra-organizational micro-blog and the social capital. With the PLS structural equation modeling method and a sample collected from 164 users with a longitudinal questionnaire survey, the results indicate that employees’ continual intention of intra-organizational micro-blog is significantly influenced by the social capital including social interaction ties, trust and identification, and employee’s continual use of intra-organizational micro-blog significantly influences the social capital including social interaction ties, trust, norm of reciprocity, identification and shared vision. Besides, the social capital is raised with the time increase of the employees’ continual usage. This study provides a theoretical guidance for the industries in establishing positive interaction mechanisms between the use of intra-organizational micro-blog and the social capital for additional enterprise competitive advantage.