In recent years, there has been a substantial change for groundwater dynamic change in northern of China, and the level of groundwater in many cities overall decline. The West Liao river plain area in Tongliao City, Inner Mongolia, is a typical ecotone between agriculture and animal husbandry, and the major water source of it is groundwater. Therefore, it is significant to study the groundwater dynamic state and its causes for reasonable exploitation and utilization of water resources and ecological environment management. The Horqin District of Tongliao City was selected as the research area. Based on the relationship between dynamic variation of groundwater, precipitation and groundwater exploitation,by using the comparison method of regression analysis, M-K mutation testing, accumulative anomaly method and accumulation slope change rate, the rate of different impact contribution for the vary of groundwater dynamic was quantitatively separated, and the driving factors also were quantitatively analyzed. The results showed that there was a significant upward trend for the groundwater depth over the years. Besides, precipitation showed clear hysteresis phenomenon for groundwater dynamic changes, and the delay period was three years. The abrupt change year of groundwater and precipitation in the study area is 1998. The contribution of climate change to the dynamic variation of groundwater in the study area was 24.5%, and the contribution of human activities to the dynamic variation of groundwater was 75.5%. The change of groundwater dynamic state was mainly caused by the human activity. The results of this research would have important practical significance for rational exploitation and utilization of water resources and ecological environment management.