The terrain model basedon fractal character can sufficiently represent the statistical texture features of theterrain. Better model and higher resolution DEM (Digital Elevation Model) data can beobtained from the lower resolution data by using fractal interpolation. The determinationof fractal scaleless range is very important for computing the fractal characteristicparameters and modeling the digital elevation. The traditional method for determining thefractal scaleless range usually adopts the mutual test between people and compute.However, this method tends to be too subjective. Hence, we offer an auto-determiningmethod, which has been proved to be concise, effective and efficient by experimental results.