Abstract: To meet the computational demands of numerical flood simulation under China’s information technology innovation initiative, this study proposes a high-performance two-dimensional unstructured hydrodynamic model designed for domestic multi-node GPU clusters. The model is based on a Godunov-type finite volume scheme and is implemented in C++ using the Heterogeneous-Compute Interface for Portability (HIP) framework, enabling efficient acceleration on domestic GPUs. METIS-based domain decomposition and the message passing interface (MPI) are adopted to support collaborative computation across multiple GPUs and computing nodes, thereby improving parallel computing efficiency. Numerical tests using the classical rectangular dam-break benchmark and the Toce River case demonstrate that the model achieves satisfactory accuracy, stable computation, and reliable inter-domain communication. Field application to Hengshan Reservoir in Jiangsu Province further shows that, for a meter-scale simulation containing 15 million mesh cells, the use of 64 GPUs across 16 nodes reduced the total runtime from 3.76 h to 15 min. This result indicates a substantial improvement in computational efficiency for large-scale, high-resolution flood simulation, reducing runtime from the hourly scale on a single GPU to the minute scale on a multi-node GPU cluster. With compatibility across domestic hardware and software environments, the proposed model has strong potential for engineering applications in high-resolution flood modeling.