Abstract: This paper aims at an empirical analysis of how relational capital of the scientific collaboration network influence affect firm's technological innovation performance,and the mediating role of firm's partners dynamic,based on 2000-2015 China's 502 biomedical engineering firms 9233 co-authored papers data to construct the scientific collaboration network and 16,754 invention patents were filed between 2001 and 2016. The data were collected from Web of Science and China National Intellectual Property Administration. The results show that the relationship breadth and relationship strength in the scientific cooperation network have a significant positive impact on the performance of technological innovation. The relationship breadth of scientific cooperation network is beneficial to the expansion of corporate partners, while the relationship strength has a positive effect on the stability of corporate partners. The stability and expansion of partners have a complete mediating effect on the impact of the breadth and strength of scientific cooperation network on the firm's technological innovation performance.