There are many bridges over the Changsha-Zhuzhou-Xiangtan section of the Xiangjiang river.In the past，when analyzing the influence of bridge construction on flood discharge capacity of the river，the influence of single bridge is mostly considered，while many river-crossing bridges will have a cumulative effect on flood discharge capacity of the river.Based on the measured river topography and hydrological data，a two-dimensional hydrodynamic model of Changsha-Zhuzhou-Xiangtan section of the Xiangjiang river is established.Based on the validation of the model，the influence of four groups of different inflow conditions on water level before and after bridge construction is compared and analyzed.The results show that the larger the flood discharge，the higher the water level is；single bridge has a certain influence range on the increasement of water level.In order to build new bridges over the river which already has many bridges，it is necessary to plan the location of bridges reasonably.