This paper applicate the digital elevation model(DEM) method in geographic information systems(GIS) on the earthwork volumes, intending to present an efficient geographic information-obtain method and an optimum earthwork volumes method after analyzing the obtain method of geographic informations which are made up of as spatial data(X, Y) and attribute data(Z), analyzing area determination method by geographic information-obtain method each other and the accuracy of earthwork volumes computation. The results of this paper showed that the method of earthwork volumes computation, which was based on the earthwork volumes-calculation grid applied by the DEM method of based grid to randomly get the geographic information of geographic transformation point and translated geography into nonlinear and unequal interval, was very efficient.