This paper addresses the emergence of water security problems in North China with the aim of highlighting key waterresources management and water security issues for the long-term development of North China. Three key problemsrelated to water resources and security issues in North China in the 21st century are addressed, namely 1) the watercycle under environmental change, 2) agricultural water saving, and 3) water security. Development of internationalresearch related to these issues is also reviewed. The research plan developed recently by the Chinese Academy of Sciences(CAS) is discussed and suggestions on research and development of water resources science in North China are presented.Thanks to focus on experimental catchments and dedicated research stations, a detailed knowledge of the water cycle onNorth China farmland has been compiled. A range of techniques that include isotope tracers has been used to acquirehydrologic data. Much research has been devoted to developing distributed hydrological models at different scales. In thewell irrigation district, five different water saving irrigation regimes have been investigated, and these regimes have hadwidespread application, and reduced water use 60-150 mm while they increased water use efficiency (WUE) by 20%-30%.Furthermore, preventing water pollution is the most essential step to ensure North China’s water security. This paper addresses the emergence of water security problems in North China with the aim of highlighting key waterresources management and water security issues for the long-term development of North China. Three key problemsrelated to water resources and security issues in North China in the 21st century are addressed, namely 1) the watercycle under environmental change, 2) agricultural water saving, and 3) water security. Development of internationalresearch related to these issues is also reviewed. discussed and suggestions on research and development of water resources science in North China are presented.Thanks to focus on experimental catchments and dedicated research stations, a detailed knowledge of the water cycle on North China farmland has been compiled. A range of techniques that include isotope tracers has been used to acquirehydrologic data. Much research has been devoted to developing distrib uted hydrological models at different scales. In thewell irrigation district, five different water saving irrigation regimes have been investigated, and these regimes have hadwidespread application, and reduced water use 60-150 mm while they increased water use efficiency (wue) by 20% - 30% .Furthermore, preventing water pollution is the most essential step to ensure North China’s water security.