Abstract: Due to the limitation of the times and uniqueness of geographical unit, the former research hotspots of city spatial structure theory mainly focused on the economically developed eastern regions or hyper-megalopolis, but paid insufficient attention on small and medium-sized city in the underdeveloped western regions. Based on RS and GIS technology, this paper made quantitative analysis on the 20 years` urban spatial expansion and morphological evaluation of Chongqing Three Gorges Reservoir Area, by employing urban spatial expansion intensity and speed index, compactness, fractal dimension and shape index as well as extracting built-up area data based on the five TM remote sensing images of 1995, 2000, 2005, 2010 and 2015. At last, we summed up the following conclusions and suggestions. Firstly, the intensity and speed of urban spatial expansion shows an increasing trend on the whole, while the compactness keeps cutting down and urban built-up area increases year by year, suggesting that the urban expansion was unstable. Secondly, when suffering from mega events, the urban spatial morphology will be prone to abrupt changes, and as time goes by, the spatial morphology will be integrated again. The third, at the first decade since Chongqing became a municipality in 1997, the resettlement project offered a good opportunity for the sudden change of urban morphology. After 2017, the key mode of urban expansion in research area is in one or two directions, which has formed the development trend of “one center, two auxiliary” under the core drive of economic development. And the forth, in the planning of future urban development, it should adhere to sustainable development, rationally planning land use, optimizing the industrial structure, strengthening environmental protection, and avoiding the passive situation of “developing with pollution”. Meanwhile, combined with the transportation advantages, the hinterlands should be established all around center town as the foundation for future expansion of constructing sub-central city, aiming at forming the city morphology along the developing center in terms of “one core, multiple wings”.