Abstract: Fangshan District in Beijing city is one of the areas with the most serious casualties and property losses caused by the “23·7” catastrophic basinwide flood disaster in the Haihe River Basin. This article takes the Huludai Village in the mainstream of Yongding River in Fangshan District and the end of Fangshan section of Yongding River as the research area, and adopts the Beijing-3 satellite to dynamically monitor and evaluate the optimization of riverbed forests in this area. Through a comparative analysis of three consecutive sets of image data from August to October in 2023 after the disaster, it was found that the forest area and the number of patches in the study area decreased by 92.55% and 83.52% respectively, and the discretization degree of forest patches increased significantly. It can be seen that the Beijing-3 satellite can effectively assist relevant departments in dynamically supervising the progress and effect of riverbed forest optimization construction, and assist in improving the safety of riverine flood discharge.