<p>Urban flood mitigation remains a critical challenge, particularly in rapidly urbanizing regions. This study aims to evaluate the flood mitigation effects of different spatial configurations and structural layouts of blue-green infrastructure networks. The CADDIES two-dimensional hydrological model and a scenario-based assessment method were utilized to explore the key factors that affected the efficiency of blue-green infrastructure network under varying rainfall intensities and duration. The key factors explored include centralized versus decentralized green infrastructure strategies, upstream versus downstream detention, and blue infrastructure density versus width. The results demonstrated that upstream small-scale decentralized detention ponds significantly reduced peak water depths and alleviated drainage pressure on main canal. Downstream large-scale constructed wetlands provide more immediate relief to downstream canals and have sufficient capacity to effectively attenuate the flow velocity, but might leave upstream areas underutilized in terms of flood mitigation. An optimal strategy may involve a balanced combination of upstream and downstream retention to distribute the benefits of flood control more evenly across the network. Therefore, it was recommended to prioritize the implementation of small-scale detention ponds in upstream areas. Moreover, if conditions permit, centralized large-scale constructed wetlands were advised for downstream regions. This study provides new insights into the synergistic interactions between green and blue infrastructure configurations. The findings offer practical guidance for designing sustainable urban flood risk management systems.</p>