Abstract: Entropy is a key index on measuring DEM terrain information content.According to the uncertainty of the influence of subset partition strategies on DEM information content,we present a new algorithm of subset partition based on the maximum entropy theory.Firstly a standard maximum entropy response curve is constructed.Then the optimal classification strategy is analyzed and calculated based on the differences between standard logarithm model and original information entropy model through the statistic characteristics of the linear slope vary and the stability of the curve.The new algorithm is proved to be efficient to avoid the subjectivity and arbitrariness in DEM artificial classifications,which provides an objective theoretical basis for DEM information entropy calculation.