The purpose of this study is to explore the water conservation value of the Beidagang wetland ecosystem in Tianjin under different scenarios, to explore the scenario plan to promote the sustainable development of the Beidagang wetland, and to provide a scientific basis for the improvement of water conservation function and the formulation of a sustainable development strategy. The Beidagang wetland is the largest wetland and an important water conservation function area in Tianjin; we take Beidagang wetland and its surroundings as an example, obtain the water conservation quantity based on the correction of the InVEST model, and estimate the value by using the shadow engineering method combined with the Fixed Asset Investment Price Index. The PLUS model was used to predict land use changes under the natural development scenario, wetland protection scenario, and tourism development scenarios in 2030 and 2040 and to predict the trend of changes in its water conservation value to provide a basis for wetland protection work and ecological governance. The results show that, spatially, the areas of high-value, multi-year water conservation value are distributed in the waters dominated by artificial wetlands. In addition, mudflat wetlands, cropland, and marsh wetlands all show a strong water conservation capacity. Temporally, from 1990-2020, the overall trend of water conservation showed a decrease and then an increase, and it was the same as the trend of rainfall change. Based on the PLUS model, it is predicted that the water conservation value in 2020-2040 under the wetland protection scenario shows a steady increase. The water conservation value and wetland area under this scenario are larger than the other two scenarios, effectively curbing the trend of construction land expansion. The various land-use types have been reasonably regulated, and this scenario is conducive to restoring the ecosystems in the study area.