This study aims to enhance emergency response and decision-making capabilities for rainstorm disasters. It begins by analyzing 87 such disasters worldwide and summarizing secondary events across 15 urban lifeline systems. Based on these findings and the characteristics of rainstorm disaster evolution and complex network theory, the study constructs a model of rainstorm disaster chains in urban lifeline systems, conducting both partial and overall analyses of this model. Using a PageRank-risk matrix, the study calculates quantitative node risk levels for different parts of the model and applies complex network theory to assess overall chain risk. The results show that the highest risk disaster chain is ‘flood → submerged or collapsed houses → damaged roads → traffic congestion or paralysis’. The most important node is ‘traffic congestion or paralysis’, underlining the acute need for emergency response measures in urban traffic systems during a rainstorm disaster. Overall, this research provides crucial direction for preventing rainstorm disasters in urban lifeline systems.