According to the situation of agricultural water use, input–output of different planting modes and agricultural non-point source pollution around the Dongting Lake area, and following the principles of data availability and operability, the model selects the utilization of water resources and production cost excluding water as the main input indicators, the gross revenue as the desirable output, and the total nitrogen and phosphorus discharge of agricultural wastewater as the undesirable output. The main input indicators select the agricultural water consumption of counties around the Dongting Lake area under four main planting modes per unit area, and other inputs excluding irrigation water cost as production cost input (production cost includes land transfer fee, labor fee, electricity fee, land consolidation, harvesting machinery, drying fee, seed, pesticide, fertilizer, and other means of production). According to the Dongting Lake water, an environment detection report provided by Hunan Dongting Lake Ecological Environment Monitoring Center, the agricultural water environment pollution of Dongting Lake is mainly reflected in the excessive total nitrogen and phosphorus emission. Therefore, the unexpected output indicators in this paper mainly select the total nitrogen and phosphorus emissions of agricultural wastewater per unit area, and use the nitrogen and phosphorus emissions indicators to measure the pressure of agricultural non-point source pollution on the water environment. The input–output indicators of the main cropping patterns in the Dongting Lake area from 2011 to 2020 and their average values are shown in Table 1.