This book constitutes the refereed post proceedings of the 6th International Conference on Spatial Data and Intelligence, SpatialDI 2025, held in Xiamen, China, during April 17–19, 2025.The 17 full papers were carefully reviewed and selected from 100 submissions. The conference focuses on generative AI and spatial data intelligence, spatiotemporal knowledge graphs and large geographic models, digital twins and smart cities, government spatiotemporal big data and data governance, emergency disaster reduction and sustainable development, spatial humanities and social geography computing, spatiotemporal data management and analysis, and intelligent processing of remote sensing images.