This paper introduced the urban expansion intensity index to study the spatial and temporal variation characteristics of urban spatial expansion in Nanchang City from 2000 to 2017. Then, the 3 km×3 km unit grid was systematically sampled to construct the landscape ecological risk index to explore dynamic changes in the landscape pattern and landscape ecological risk. Finally, by using the geographic weighted regression (GWR) model, the relationship between urban spatial expansion and landscape ecological risk in Nanchang City from 2000 to 2017 was quantitatively analyzed to explore the impact of urban land expansion on landscape ecological risk. The results showed that:(1) From 2000 to 2017, urban land use in Nanchang increased by 247.56 km², with an average annual expansion rate of 17.75 km². Among them, the fastest expansion strength was 0.55 in 2000-2005, showing a dramatic change. The urban expansion mainly expanded to the north and northwest, and was distributed in the Qingshan Lake District, Nanchang County, and Xinjian County, among others, which showed a rapid expansion trend; (2) The landscape pattern of Nanchang City was dominated by cultivated land, and the construction land was expanding rapidly. The area of cultivated land, forest land, and grassland continued to decline, and the landscape pattern index of land use reflected that the degree of disturbance of human activities increased during the period, the number of landscape patches increased, and the overall fragmentation increased. By using the geostatistical analysis method, the ecological risk of Nanchang City increased from 0.1354 to 0.1420 between 2000 and 2017, and the ecological risk gradually increased. (3) From 2000 to 2017, there was a negative correlation between urban land area and landscape ecological risk, the urban spatial expansion intensity index, and the landscape ecological risk change value, with the latter weakening. The spatial distribution of the regression coefficient gradually increased from the central part to the outside, and the low value was located in the Nanchang urban area where the urban expansion was relatively fast. The rapid expansion of the urban area has greatly increased the urban area, and the degree of fragmentation and loss degree have been reduced. Ecological risks are reduced. High values occurred in areas with slow economic development, such as Jinxian County and Anyi County. With a small extend of urban land use and large degree of extended boundary patches, the ecological risk of the landscape increased. The research results could promote the coordination between urban construction and ecological environmental protection, correctly evaluate the impact of human activities on urban ecosystems, and provide references for sustainable development and scientific management in Nanchang.