[Objective]As a crucial water conservation functional area and ecological buffer zone for the Beijing-Tianjin-Hebei (Jing-Jin-Ji) region, predicting the water conservation function of Chengde City under various scenarios is of significant importance for ensuring regional water security and optimizing territorial spatial planning.[Methods] Utilizing a coupled PLUS-InVEST model, four scenarios (Cropland Protection, Ecological Protection, Natural Development and Urban Expansion) were simulated to predict land use patterns and water conservation function in Chengde City for 2038, followed by coupling analysis.[Results]Under different scenarios, forest area remained relatively stable, while grassland, cropland, and impervious surface exhibited the most significant changes. Grassland area decreased in all scenarios except Ecological Protection. Cropland area decreased by 4.1% under Ecological Protection, while impervious surface area increased markedly by 38.5% under Urban Expansion. The average water conservation capacity per unit area was generally similar across land types, following the pattern: Grassland > Cropland > Forest > Bare Land > Impervious Surface > Water Body. However, total water conservation volume varied considerably. Forests provided long-term stable water conservation, with a total volume of approximately 530 million m3. Grassland water conservation was lowest under Cropland Protection (261.84 million m3) and highest under Ecological Protection (300.72 million m3). Cropland water conservation was highest under Cropland Protection (220.98 million m3) and lowest under Ecological Protection (185.34 million m3).[Conclusion]Strictly protecting the forest ecosystem, while coordinating the balance between cropland protection and ecological space (especially grassland) restoration, and rigorously controlling the disorderly expansion of impervious surface are the key pathways to enhance regional water conservation function and support the sustainable development of the Jing-Jin-Ji region.