Groundwater is the key factor that supports the social and economic development and ecological security of West Liaohe Plain area. In order to determine the change trend of groundwater depth in the region and the dominant factors, we analyzed the evolution trend of groundwater depth, determining the dominant factor affecting the relationship between water recharge and discharge in the area according to the principle of water balance. The groundwater recharge before 2000 was abundant, with irrigation water discharge less than recharge, thus groundwater balance was achieved and the groundwater depth was maintained. Average annual precipitation from 2000 to 2009 was only 75.9% in the 1990s, and the recharge of groundwater was significantly reduced, with discharge of groundwater that could be mined being decreased obviously under the condition of the balance of discharge and recharge. However, the irrigated area had developed to a higher level at that stage, and irrigation water had maintained at a higher level, thus the drainage of groundwater balance was broken. Therefore, groundwater recharge reduced to some extent that caused by the decrease of water resources system quality and global climate change, which combined with the large mining of groundwater for several years, leading to the increasing of groundwater depth. In order to solve the contradiction between supply and demand of regional water resources, we not only need to improve the level of water utilization, reduce water consumption, but also need to enhance the capacity of solving the problems as it comes up.