Citing the improved "dynamic threshold method" and centroid model, the spatiotemporal characteristics of urban dynamic expansion in Jiangsu Province were analyzed, revealing the spatial distribution and regional differences of the built-up areas in urban areas of Jiangsu Province. The results indicate that during the period from 2000 to 2021, the extracted urban built-up area matched reality, and its evolution pattern aligned with urban economic development. A "radiating" agglomeration pattern centered around Nanjing, Suzhou, and Xuzhou was formed. Different cities exhibited varying expansion speeds at different stages. The development center gradually shifted from south to north, transitioning from a development pattern dominated by the Nanjing metropolitan area and the Suzhou-Wuxi-Changzhou metropolitan area towards a more balanced development model.