Abstract: Based on field investigation and by using isotope (D, 18O and 3H) and the water chemistry methods, this paper has identified the water source of groundwater for Northern Shandong Plain, estimated the supplying amount from Yellow River and revealed the hydrological cycling feature in the Yellow River downstream plain area. It is indicated that the major charging source of shallow ground water of Northern Shandong Plain is local precipitation and Yellow River water, and the proportion varies along as the distance away from the Yellow River. In total, precipitation accounts for 86%, and 14% for the Yellow River water. As to deep ground water, it’s originated from ancient precipitation which seeps underground in a much colder climate.