Abstract: Scientific collaboration plays a key role in producing scientific knowledge, which is vital to the success of firm technological innovation. We investigate 585,348 co-authored research papers published in the Web of Science during 2000 to 2017 in disciplines relevant to the new energy vehicle industry. We discovered 139,090 inter-organizational scientific collaboration ego-networks involving 32,715 Chinese organizations. Meanwhile, we collected data on 16,112 patents applied by 1,893 Chinese organizations in the industry from the Derwent database. We use co-authored papers and patents applied by 174 focus firms and other organizations as panel data to empirically analyze how scientific collaboration network relation affects firm innovation in Chinese new energy vehicle industry. The study findings show, both relation breadth and relation strength in the scientific collaboration network can positively affect firm innovation, and the relation strength has a more direct impact than the relation breadth. Knowledge diversity (interdisciplinary and technology diversity) are mediating variables between network relations and firm innovation. Interdisciplinary is a mediating variable between relation strength and firm innovation, while relation breadth influences the firm innovation through technology diversity. Besides, both interdisciplinary and technology diversity are beneficial to firm innovation.