Nowadays the water resources shortage and pollution of North China Plain is very prominent. Especially groundwater is the main water source and supply. To build a groundwater model and integrate it into the geographic information system (GIS) is an important method to realize the sustainable use and management of water resource of North China Plain. As a result of the clear construction and independent modules of groundwater model program MODFLOW,which is based on the finite difference method, the original program packages could be modified and the new package could also be added into it according to the needs of integration. In this paper the integration relationship between groundwater model and GIS was established after analyzing the input and output data format of groundwater MODFLOW and the geological and hydrogeological data format of North China Plain where most data were mainly composed of MAPGIS format. And it was applied to the groundwater evaluation of North China Plain. According to the hydrogeological condition of North China Plain, the three dimensional transient groundwater flow model was constructed. Parameters were validated using flow net of observation pores in December 2003. and the dynamic water level data between January 2002. and December 2003. The parameters include conductivity coefficient, specific yield and storativity of aquifers. During the process of constructing the groundwater model, a water budget was analyzed, which resulted in a negative budget in the North China Plain. The simulation period was from January 1,2002 to November 12,2003. During this period the total recharge of the groundwater system was 493.74 10⁸m³,and the total discharge was 565.30×10⁸m³,and the budget deficit was -71.56×10⁸m³. The system with groundwater of North China Plain can dynamically evaluate the groundwater resources under the net circumstance by using the source and sink data in database which can provide reference valuable for the use and management of water resource.