Abstract: China is one of the countries that are most severely affected by floods disasters in the world. With the rapid development of social economy, the direct economic loss caused by flood is becoming more and more serious. Consequently, the flood control strategy in China is transformed from flood control to flood management. The flood management needs flood risk analysis of which the numerical simulation is a crucial method. Based on flood risk mapping pilot project (phase II), the Jiaxing area is chosen as the research object to establish a one-dimensional river network model to simulate water level changes by MIKE 11 . Followed a two-dimensional model is established to simulate flood routing process for rainstorm by MIKE 21. Finally, the dike-break flood routing process in the research area is simulated by MIKE FLOOD coupling model to analyze the flood risk and provide technical support for flood management in Jiaxing area.