River is one of the most important part of urban ecosystem while the contradiction between the rapid urban growth and river protection is usually inevitable, especially within developing polder areas with the increasingly serious pollution problems. In addition to traditional methods such as land planning or pollution control, the artificial design of river connections is also a possible solution. In current study, a method for designing river connection in polder areas was proposed based on the graph theory, which utilizes the community search as an optimization method. The polder river ‘communities’ was analyzed by applying integrated water head loss as the weight in the network, which enables the optimization and selection of connection plans. A case study was carried out on 133 rivers in Wusong polder in China, where 8 candidate plans were identified. The performance of these plans was hydrologically evaluated under the current water diversion plan. Results indicates that the optimized connection plans could reduce the proportion of dead channels (11.0% → 6.47%) and increase that of activated channels (55% → 57.5%) with negligible impact on the maximum and average velocity in the polder area.