In recent years, flood disasters are one of the most frequent and most severe meteorological disasters in the world. Many domestic scholars began to study flood disasters,but there is currently little research on flood disaster risk in Dongting Lake District.In this paper, a comprehensive evaluation method is used to establish a model to evaluate the flood disaster risk of Lanni Lake water system in Dongting Lake area and propose countermeasures. The results show that under different internal water levels of Xinquansi Sluice, different rainstorm intensities have different impacts on the flood disasters of the Lanni Lake water system. At the same time, raising the waterlogging surface rate and lowering the water level of the inner lake can basically eliminate the high-risk range in general years, which is more significant in reducing the low-risk areas and increasing the non-risk areas,and reduce most high-risk areas for years with a high average risk.