Abstract: The global error of digital elevation model(DEM) comprises the propagation error of grid data and the simulation error of terrain represented by interpolation method.The experimental results show that the differences of different DEMs' global errors reduce gradually with the original data error increased in same terrains,in the end to zero.In different terrains,the DEM's global error is different when the original data error is different even if the interpolation method is the identical.As shown in experiment,the precision of digital elevation model not only relates to sampling intervals and terrain complexity but also relates to interpolation methods and original data errors.Different DEMs have different sensitivity to original data error in different terrains.Hence,we present the way to select appropriate interpolation method.