This research aims to facilitate the gradual transition of traditional irrigation districts into ecological ones, offering decision-making support and references for their sustainable development. Focusing on the main canals of the Ganfu Plain Irrigation District, this study established a comprehensive water ecological health assessment system based on the entropy weight method. The assessment framework integrates eight indicators categorized into three groups: water quality parameters (dissolved oxygen, total phosphorus, etc.), benthic macroinvertebrate community structure, and habitat quality (HQI), and a corresponding five-level grading standard was established. Combining field investigations and quantitative analysis via the entropy weight method, the study achieved an objective and quantitative evaluation of the water ecological health status of the irrigation canals. The results showed that the overall water ecological health of the study area was at the fair-good grade (comprehensive score: 52-77). Among the sampling sections, the old Fuhe River section performed excellently (score: 82, rated as great) due to its superior habitat integrity and biodiversity. This study is the first to systematically incorporate habitat quality parameters into an ecological assessment framework for irrigation districts, effectively revealing the spatial heterogeneity of water ecological health along the canal system. Despite limitations related to seasonal sampling bias and regional standard variations, the results objectively reflect the actual water ecological conditions of the main canals in the irrigation district. The findings provide a scientific basis for environmental management and ecological restoration of irrigation districts, and offer technical support and decision-making references for safeguarding water ecological security in the Poyang Lake Basin.