Abstract: The firm size of big enterprise is not a necessary condition to realize the continuous innovation of the industry which they belong to. In this paper, we introduce the conception of firm size quality in the issue that big enterprise act as the innovation source, we abstract the problems of China’s industrial upgrading, including the issues of low industrialization, weak big enterprises and traditional industry’s upgrading, as firm size thresholds, and the breaking through these three size thresholds constitutes the connotation of firm size quality. On this basis, we establish multiple  assumption on big firm’s leading effect on industrial innovative upgrading, with 201 samples from national and provincial innovative enterprises, and verify the direct effect that firm size quality has on industrial innovative upgrading, incomplete mediating role of collaborative innovation and adjustment role the entrepreneurship acts in big enterprise. At last, we conduct an extended discussion on phase characteristics of industrial upgrading by breaking through firm size thresholds and the duality of characteristics of big enterprise in the process of leading the industrial innovative upgrading.

Key words: firm size quality, firm size threshold, multidimensional collaborative innovation, big firm’s entrepreneurship, industrial innovative upgrading