Abstract:    Complex product systems have unique characteristics of technology and market regime, and latecomers are faced with catch-up challenges such as cold start paradox, technology accumulation difficulty and path dependence dilemma. Based on the longitudinal case study of China′s shield machine industry from catch-up to beyond, this paper explored the user participation features and innovation operation patterns in the process of technology catch-up of complex product systems, and expanded the path reference and management insights for the technology catch-up of complex product systems in deepening the research on subject interaction of national innovation system theory. This research found that key users with specific product requirements and significant industry influence fully participate in the innovation process and deeply influence decision-making. From the aspects of subjective collaboration, innovation effectiveness and learning effects, users drive the technological catch-up of complex product system industry. They have advantages such as application demonstration and learning of mature technologies, industrial-level collaboration, and frontier value propositions in addressing catch-up challenges. Furthermore, key users play a critical role in knowledge integration, scenario orchestration, and system coordination within the collaborative industrial modes of national innovation systems focused on the beyond catch-up, driving technological innovation and rapid catch-up in the complex product system industries.

Key words: complex product system, key user, beyond catch-up, national innovation system, longitudinal case study