<p>To investigate the spatial transmission patterns of flood disaster chains and the coupling mechanisms of lifeline facilities in complex urban environments, this study proposed a flood disaster chain propagation model based on coupling pathways among exposed units, focusing on the coupling pathways of power, transportation, and communication infrastructures. By integrating remote sensing and GIS data, we identified the spatial distribution and functional dependencies of exposed units. A functional degradation model was developed by combining water-depth vulnerability functions with inter-facility coupling pathways to simulate direct flood impacts and cascading failures. Taking the main urban area of Chongqing as a case study, we simulated the evolution characteristics and spatial transmission patterns of the disaster chain during a typical 2020 flood event. The results indicate that as the disaster chain shifted from isolated failure pathways to compound coupling cascades, the chain effect significantly amplified both the scope and severity of system disruptions. Model outputs show strong consistency with historical damage records in both spatial distribution patterns and magnitude, thereby validating the model’s effectiveness in disaster chain identification, vulnerable node detection, and risk prediction. These findings provide a scientific basis for systematic prevention, risk assessment, and emergency decision making in urban flood management.</p>