Abstract: As groundwater researchers know, it is difficult to obtain basin-wide, distributed hydrngeological data and aquifer parameter data, especially in a large-scale watershed. In this research, the direct inverse method is employed to resolve the problem of identifying distributed aquifer parameters in a basin. The direct inverse method is faced with the So-called ill-posedness problem that makes the equations yield no solution. In order to overcome this difficulty, the non-optimization solution scheme is adopted. This model is validated by an application in the Kanto Plain, Japan.