<p>Urban networks have become important channels for the co-development of urban clusters. However, networks not only enable the sharing of development resources but also transmit potential risks. Accordingly, it is not yet clear how urban shrinkage risks spread through urban networks, which poses a significant challenge to sustainable urban development. The current study introduces the susceptible-infectious-recovered-susceptible (SIRS) epidemic model to discuss the contagious effect of urban shrinkage risks. The urban investment network is built on the basis of the external investment relationships between listed enterprises in Northeast China. The investment network is characterised by a small-world network and a core-periphery structure, and the in- and out-degree centrality of cities is not balanced. Additionally, the results generated by the SIRS epidemic model revealed that the initial source of infections affects the spread rate of the shrinkage risk. The infection rate has the greatest impact on the spread of urban shrinkage risks compared with the recovery rate and immunity loss rate. Further, there is a threshold effect on shrinkage risks, which means that a shrinkage risk originating from anywhere can rapidly propagate throughout the entire region when it reaches a certain threshold.</p>