Baiyu Mountain lies in central part of the Ordos Basin at east-west direction, spanning the north of Shaanxi Province and belonging to low-medium loess hills. Based on field analysis of hydrodynamic force, hydrochemistry and isotope, Baiyu Mountains is a watershed in between the Wuding River and the Luohe River on the surface, and also an underground watershed between the Quaternary loosed beds and the Cretaceous Huanhe Formation, which is not an underground watershed of deep buried Cretaceous Luohe Formation. The underground watershed of the Luohe Formation is 4 km～17 km north to Baiyu Mountains, which would be favorable for further development of underground water from the Cretaceous Luohe Formation.