As one of the largest countries in the world, China has a highest population and great potential in water resources and land. Water is a key issue for sustainable development in the fu-rure, because the average water and land availability per-capita is much lower than the world averages. Water resources assessment plays a very important role. However, certain problems could not be solved due to lack of hydrological data, such as groundwater in arid and semi-arid zones. Environment isotope technologies have been applied and show promise of wide application. As a one of the largest countries in the world, China has a highest population and great potential in water resources and land. Water is a key issue for sustainable development in the fu-rure, because the average water and land availability per-capita is much However, certain problems could not be solved due to lack of hydrological data, such as groundwater in arid and semi-arid zones. Environment isotope technologies have been applied and show promise of wide application.