Three factors, i.e. surface amplitude, incision density and incision depth are used to quantify the broken index of surface in order to study broken degree of surface. Based on the DEM, the calculation and extraction of single elements are finished by using GIS. Based on fuzzy clustering and rough set theory，a method is put forward to determine the influence coefficients of single elements in the composite element, and the formula of composite elements-the broken index of surface is elaboratcd to finish the calculation in Shandong Province. The calculation results indicate that a highly spatial heterogeneity exists in the broken index of surface in Shandong Province and it objectively shows the distribution of the broken degree of surface in Shandong Province and provide a basis for the zoning of highway and land division.