Computing infrastructure is a vital component of new information infrastructure. It can reshape the flow paths of digital knowledge and provide important support for the technological convergence of digital and real economy industries. Based on data of telecom business operating licenses from the Ministry of Industry and Information Technology and Chinese patent application data from 2010 to 2023, this paper empirically examines the impact and internal mechanisms of urban computing infrastructure construction on the technological convergence of digital and real economy industries, using digital knowledge as the key intermediary carrier. The results show that urban computing infrastructure construction can significantly promote the technological convergence of digital and real economy industries. Mechanism testing indicates that computing infrastructure construction facilitates the efficient circulation and sharing of digital knowledge factors, enables the rapid penetration of digital knowledge into all links of the industrial chain, and thus drives the technological convergence of digital and real economy industries. Heterogeneity analysis reveals that this promoting effect is stronger in eastern cities, cities above the third-tier, non-resource-based cities, and cities belonging to national-level urban agglomerations. Based on the above conclusions, this paper draws the following policy implications: First, accelerate the construction of urban computing infrastructure and strengthen the supporting role of computing power supply in the technological convergence of digital and real economy industries. Through policy instruments such as fiscal subsidies and tax reductions, cities should be guided to increase investment in core fields of computing infrastructure in accordance with their own industrial foundations. Second, take the construction of urban computing power networks as the starting point to improve the mechanisms for digital knowledge flow and sharing. On the one hand, efforts should be made to promote the coordinated application of computing power, algorithms, and data within cities, and to build city-level computing power sharing platforms. On the other hand, the linkage of urban computing power networks within large urban agglomerations should be enhanced to establish cross-city alliances for computing power and digital knowledge sharing. Third, promote the construction of urban computing infrastructure in a hierarchical and classified manner based on heterogeneous urban characteristics. Central cities should focus on building real-time computing power hubs to meet low-latency and high-computing-power demands, while peripheral cities should develop green computing power bases and ultra-large-scale data center clusters, mainly undertaking non-real-time computing power needs.