Abstract: Groundwater system study is an important base to assess regional groundwater resources and to set up the rational groundwater development patterns. Based on lithopaleogeography of the waterbearing media and its spatial distribution of Ordos Cretaceous artisan basin（CAB） and the features of regional groundwater flow regime,hydrogeochemistry regime and monitoring data about the groundwater level and isotopic analysis at different depth sampled by Packer sampling system in the deep drilling holes, the authors have explored the main characteristics of the groundwater systems in CAB. The groundwater flow system in CAB can be classified into three types: local flow system, medium flow system and regional system. Bordered by the surface divide of Baiyushan Mountain, the CAB can be divided into two groundwater subsystems and five groundwater branchsystems. Among them, the groundwater subsystem in loess playa in south CAB is characterized by typical artisan basin and the groundwater subsystem in desert playa in north CAB is typical of phreatic basin.

Key words: Ordos, Cretaceous Artisan Basin（CAB）, waterbearing system, groundwater system