Abstract: Passing through the abdomen of the Taihu Lake basin from north to south, the South Jiangsu (Sunan) Canal has the functions of navigation, flood control and drainage, irrigation and landscape. In recent years, the water level of the canal has exceeded the historical high level, causing serious disasters along the canal and its surrounding areas. The refined hydrology-hydrodynamic model developed by us can provide technical means and scientific basis for the cause analysis of the high water level of the canal, the decision-making of flood control and drainage, and the benefit evaluation of new and old works. Based on the Infoworks ICM software, the hydrology-hydrodynamic model of the plain river network along the South Jiangsu Canal is built, taking into account the polder area, urban pipeline network and complex underlying surface of the plain river network along the South Jiangsu Canal. In view of the difficulty in determining the boundary of the river system along the South Jiangsu Canal, the study area of the model has been extended to 21,600 km². The model is validated and calibrated using the actual rainfall, water level and water conservancy work operation data in the flood seasons of 2015 and 2016. The verification results show that the refined hydrology-hydrodynamic model for the Sunan Canal has high credibility and can provide a technical support for academic research and engineering application. The Nash coefficients of most hydrological stations are close to 1, and the reliability of the model is high. The determination coefficient results show that the correlation is moderate, and the overall results of the model are credible. At the same time, compared with other areas of the Taihu Lake, the simulation accuracy of the western area of the Taihu Lake is higher. The main reason is that the western area of the Taihu Lake is less intervened by man-made dispatching.