In order to research the process of flood routing in the marsh land detention area of Enxian county，the paper used EFDC model to simulate the two-dimensional flood routing in accordance with different terrain conditions. Two different flood schemes were designed to compare and simulate. The result indicated that outflow in the detention area has great impact on flood routing.The simulation effect of two-dimensional flood routing by EFDC model is very well. The research can provide technical support and way for flood control and disaster reduction in flood detention basin.