Abstract: Under the innovation-driven development strategy, Chinese city clusters are transforming from factor agglomeration to collaborative innovation paradigm. Based on the multi-dimensional proximity theoretical framework, there exists a dynamic matching mechanism among geographic, industrial, cognitive, and institutional proximity, together shaping the spatial path of innovation factor flow, the diffusion mechanism of knowledge overflow, and organizational logic of network collaboration. Specifically, geographic proximity strengthens the material carrier foundation for collaborative innovation by reducing the cost of factor spatial flow and promoting the silent transmission of tacit knowledge. Industrial proximity drives the regional industrial competitiveness to leap up by relying on the vertical integration and horizontal synergy of the industrial chain. Cognitive proximity strengthens the cognitive synergy among innovation subjects through the decoding of technological paradigms and the sharing of cross-domain knowledge. Institutional proximity builds a systematic guarantee system for the free flow of innovation factors by means of collaborative policy governance and administrative barrier removal. The institutional optimization of collaborative innovation in China's city clusters presents the driving feature of the two-strength engine: on the one hand, through the construction of a high-standard technology market system, we strengthen the protection of intellectual property rights and the market allocation of cross-regional innovation resources; on the other hand, relying on the advantages of the new state-run system, through the top-level institutional design, policy synergy, and the creation of an innovation ecosystem, we realize the dynamic balance and collaborative evolution of multi-dimensional proximity.
