Abstract: This paper discusses several important factors in selecting interpolation methods.Firstly,the characteristics of the ground surface are briefly discussed.Ground surface is not a single surface with a high level of smoothness,but a combination of many low-order surface patches that connected with each boundary edge.Then,the accuracy of the given ground data is analyzed,and calculation stability is one important problem which must be evaluated in DEM interpolation.Finally,it states that the ability of preserving the topographic orderliness by the interpolation method is necessary to be considered.Relatively speaking,various interpolation methods can provide an acceptable approximation behaviour if the sampled points is dense enough,but it is suggested that the high-order interpolation should be used carefully.