Abstract: Abstract：In this paper, the current status of groundwater quality study in China is reviewed briefly firstly. In view of the disadvantages of traditional methods, a set of means for regional groundwater evaluation based on Arcgis system, which can not only process mass samples but also map the assessment results automatically, is put forward. The outputs of this method preserve the very poor point which was likely to be overlooked in the past. The evaluation results based on more than 3000 groundwater samples collected from 1035 wells in Beijing Plain show that from the shallow part to the depth, the quality of groundwater in Beijing tends to become better. The analytical results show that the main excessive components of the groundwater samples are total hardness, TDS , Mn, NH-4, Fe, F-, NO-3 and NO-2. The total area belonging to class IV and V is 3649 km2, 2258 km2 and 737 km2 respectively for shallow, middle and deep groundwater. Also, the comparative results show that on the whole the groundwater quality in the wet period is slightly worse than that in the dry period within Beijing Plain.