Abstract: The river network area of the southern plains of China is crisscrossed by rivers, but the slow-moving water in cut-off ditches and streams results in a weak self-purification capacity, contributing to agricultural non-point source pollution. To enhance the water purification functions of ditches and rivers in the plain river network area, it is imperative to integrate their characteristics and implement collaborative management strategies of ditches-ecological ponds-disconnected beaches-stream adaption to local conditions. In this study, we focused on the typical ditches and rivers in the Taihu Lake Basin with the aims of investigating the spatiotemporal dynamics of N and P migration, identifying the main influencing factors, and clarifying the impact of different ditch-pond management strategies on N and P removal rates. Through continuous in situ monitoring of N and P concentrations changes within ditches and ponds during the rice growth season, we assessed the effects of three modes of coordinated management of ditch-pond: fully enclosed, semi enclosed, and fully open. The results showed that, during the rice growth season, NN₄⁺-N、TN and TP concentrations in ditch and pond water decreased and stabilized 7 days after fertilizer application, highlighting fertilizer application as the main factor influencing N and P concentrations. Spatially along the water flow pathway from rice field to the entrance of the river, the different ditch-pond coordinated management measures were the key factors influencing N and P migration. Under the three coordinated management measures for ditch-pond systmes, the average TN and TP removal rates under fully enclosed mode are 45.15% and 55.40%, respectively. Notably, the drainage from the fully enclosed ditch-pond was diverted to farmland after storage, therefore the environmental risk of pollution to surrounding water bodies was relatively small. The semi enclosed mode demonstrated excellent purification and absorption of N and P in paddy drainage. Full-growth stage, the concentrations of TN and TP showed a decreasing trend,with average removal rates of 60.28% for TN and 74.75%, respectively, considerably reducing the pollution risk to the receiving river. In contrast, the fully open mode showed lower removal rates of 22.27% for TN and 18.18% for TP, yet it still contributed to N and P removal. Overall, the coordinated management of ditch-pond for N and P interception and purification was effective in maintaining surface water quality standards and reducing the pollution risk to the surrounding environment from paddy drainage.