Abstract: Focusing on the application of forecast-based scheduling in optimization decision-making for complex urban water supply network systems, this study proposes a conceptual framework integrating hydrological and rainfall forecast information. By holistically considering practical constraints such as reservoir structural integrity, downstream flood control requirements, water treatment plant intake capacity, maximum allowable pipeline flow rates, and urban water supply reliability, an optimization decision-making model for complex urban water supply networks was developed with dual objectives: maximizing reservoir group safety and optimizing economic efficiency. The model was successfully applied to Ningbo's municipal water supply network system, validating its operational effectiveness. Case study results in Ningbo City demonstrate that the model effectively adjusts scheduling strategies and coordinates reservoir operations based on forecasted hydrological conditions prior to flood events. The proposed approach maintains a high operational safety level (100% water supply guarantee rate) while achieving 41.3% water resource utilization during flood periods, successfully meeting design requirements. This research provides both technical guidance and theoretical foundations for optimizing complex urban water supply network systems.