Karst Water play an important role for water supply worldwide, especially in the carbonate areas. Jinci karst spring is one of the most famous scene spots in northern China, with c.a. 3500 year's history. In this study, hydrogeochemical stable isotopes and geochemical modeling were employed to identify the major flowpath and to depict the flow system of this deep buried karst system. Two major flow path were identified successfully and the flow system was depicted with some major modification on the basis of old version. The karst water from the west deep buried area is estimated to contribute about 25-30% water supply for the The main runoff belt along the fault.