A study was carried out to assess groundwater vulnerability in the lower reaches of the Liaohe River Plain over a number of years. Groundwater bodies with a relatively stable quantity of water, good water quality, and a high degree of resistance to pollution are widely distributed throughout the world, and they have many different roles, including as domestic water supply, in economic development, integrity maintenance of the geological environment, and ecological balance. The rapid development of the social economy and subsequent increased demand for natural resources has resulted in an increased pressure on groundwater and has led to its over use. Consequently, groundwater systems in many regions and countries all over the world are exposed to varying degrees of pollution and destruction, resulting in an increasingly pronounced contradiction between supply and demand for water resources. Due to changes in the parameters affecting ground water, the spatial-temporal distribution of groundwater vulnerability is dynamic; hence, the analysis of spatial-temporal evolution and its structural variation is important when attempting to prevent groundwater pollution. The parameters affecting ground water, combined with the DRASTIC model and human factors, were used to calculate groundwater vulnerability in the lower reaches of the Liaohe River Plain in 1991, 2000, and 2010. We also analyzed the evolution of groundwater vulnerability using ArcGIS and the change in the proportion of different levels of groundwater vulnerability. The hot and cold spots for groundwater vulnerability were calculated using Getis-Ord G_i^*, and the dynamic changes in hotspots were quantitatively analyzed using gravity and the standard deviational ellipse method. In 1991, the groundwater vulnerability was low in 36.5% of the study area and high in 31.3% of the study area. In 2000, the moderate and high groundwater vulnerability areas reached 31.6% and 25.9% of the study area, respectively, while in 2010, groundwater vulnerability was high in 41.71% of the study area. Groundwater vulnerability in the study area showed a decreasing trend from 1991 to 2010 High groundwater vulnerability areas were diffused from the center of Shenyang to South coast. Hotspots were mainly distributed in the western zone of Xinmin City and Liaozhong County in 1991 and 2000, and only small changes occurred during this period, whereas the coastal areas became hotspots in 2010. Cold spots were relatively small and fragmented from 1991 to 2000. During the same period, the gravity center of hotspots shifted 2.264 km southwest, and the hotspot distribution pattern had an east-west direction. From 2000 to 2010, the gravity center of hotspots shifted 30.787 km southwest, the long axis of standard deviation ellipse was rotated counterclockwise by 32.44°, and the overall distribution pattern for hotspots had a northeast-southwest direction. In addition, the improved DRASTIC method that was used to investigate nitrogen concentration at the monitoring points and calculate the corresponding vulnerability ratio proved to be an important analysis tool. Spatial-temporal evolution of groundwater vulnerability, when investigated through the assessment of groundwater vulnerability and hot-spot distribution, may improve the utilization of groundwater and lead to the development of a protection plan for the study area.