A new numerical method, Conjunct Finite Element-Boundary Element Method (CFEBEM), is proposed here to carry out the calculation of ground water flow and the inversion of hydro-geological parameters. The CFEBEM differs from the BIEM-FEM (Liggett, 1983) and the CFBEM (Brebbia, 1980) m setting up the eguation set of global system and defining the variables on the Interzonal Boundaries (IB). The Node Set on the IB and the Conjunct Eguation Method are employed for CFEBEM, whereas the Substituting Variable Method is used for the BIEM-FEM and the CFBEM. The CFEBEM can make division of zones more flexible than the BIEM-FEM and the CFBEM. The CFEBEM shows the flexibility of the FEM and the high accuracy of the BEM So The CFEBEM can be used to solve problem of the forward and inverting calculation in ground water system with complex structures. An application to the groundwater system of Taiyuan area has demonstrated the efficiency of this technique.