China faces a very serious situation of water resources, with increasingly conspicuous problems of water resources shortage, serious water pollution, deterioration of the water ecological environment, and so on, which have become major bottlenecks inhibiting sustainable economic and social development in the country. The main manifestations are as the following: China has water resources of 1700 m3and a little more per capita, which is close to a country with water stress. Especially, the quantity of water resources per capita in JingJinJi region is even less than 250 m3, with a situation of extreme water scarcity and a serious groundwater overextraction; On the whole, the quality of surface water in China is becoming well, while the quality of groundwater deteriorates in the east coast populated area; The water supply component in some regions and cities is single water source that causes low abilities to resist sudden water source pollution and drought. Groundwater is an affordable and reliable water supply source which is established by international communities. Groundwater is a dominant drinking water source in Europe and America. Groundwater plays important roles in China for drinking water and production and irrigation uses. However, the importance of groundwater in ensuring water safety is not identified widely by public, and even ignored. This paper illustrates importance of groundwater in ensuring water safety and raises strategic countermeasures to lift abilities of ensuring water safety. The core of ensuring water safety is to push the idea transformation of harnessing water; and the key of ensuring water safety is to strengthen the innovation of hydrogeology and related subjects. The major strategic measurements include: (a) transformation from focusing on urban and industrial watersaving to focusing on systemic watersaving for making up the increase of water uses in urban areas by watersaving in agriculture; (b) transformation from focusing on development and utilization of water resources to focusing on nourishing and protecting them for promoting sustainable utilization of water resources by nourishing and protecting them; (c) transformation from focusing on surface water supplies to focusing integrated management and optimal allocation of groundwater and surface water for addressing sudden water shortage by reserving strategic groundwater; and (d) transformation from focusing on water transfer projects to focusing virtual water trade for regulating longterm water supplydemand relations by implementing virtual water trade.