More than 90 papers of the last 20 years on nitrate pollution in groundwater were reviewed, and the issue both in China and abroad was found focusing on the following aspects： the transform processes and mechanism of nitrate in groundwater, the form of pollution and the sources of nitrate, and the methods to avoid and treat nitrate pollution. The transform processes include： mineralization-immobilization, fixation, nitrification and denitrification. All kinds of nitrate are classified into point origin and area origin. There are two approaches, structural approache and non-structural approache, reported to deal with nitrate pollution in groundwater. The structural approach was well reported to dispose of nitrate in a local or point scale, while the non-structural approach could be adopted in the regional scale, but few case studies were reported. Techniques to treat nitrate pollution were well reported in China, e.g. carbon dioxide regenerated ion exchanger, bio-film-electrode process, etc. Nitrate pollution in groundwater is closely related to human activities, and the main sources of nitrate were identified as excessive application of commercial fertilizers, manure, and the irrigation by non-treated wastewater, etc. The main factors affecting the occurrence, distribution and change of nitrate in groundwater were identified as： · Dramatic increasing in population that requires much more food supply, · Urbanization that discharges too much waste to be absorbed by soil and water bodies, · Over use of fertilizer, · Poor management in water and land resources, · Land use and land cover change, · Public concern and policy issues, · Change in global food production and trade Three themes were thus proposed for further study in nitrate, given as follows： 1. Integration of nitrogen and water cycle and processes, with respect to nitrogen aspects of hydrological cycle (NAHC)； 2. Interface processes and mechanism regarding nitrate transformation in soil, plant, atmosphere and groundwater； 3. Impacts of nitrate in groundwater in the interaction of land and ocean, and assessment of human activities, such as urbanization, food production and trade, on the change of nitrate in groundwater in the global perspective.