Abstract: As a typical plain river network region, the area of Yangcheng and Dianmao is a low-lying land with serried rivers and lakes distributed. To prevent flood, 366 polders were constructed in the area, accounting for about 50% of the total geometric area. The polder area construction played an important role in flood control and waterlogging drainage in the low-lying areas of plain river network. But with the expansion of the polder areas and raised standard of flood control and waterlogging drainage in polder area, the water level in the main river rises a lot under the same flood, which has a large impact on the flood control in this area. Based on plenty of measured data and investigation on the current situation of the polders, a numerical model that reflects current river network and polders is built and the influence of polder waterlogging drainage on flood control is analyzed quantitatively. The model and analysis results can provide theoretical basis for construction of the polder areas and flood control planning of Yangcheng and Dianmao area.