In this paper

we uses Digital Elevation Model（ DEM） with three different scales in 78 study areas to calculate multiscale relief

and tries to ascertain the evaluation model of relief and to calculate the optimum statistical unit. The experiment result shows that the relief of the same experimental area with different scale exists a certain extent of difference

the smaller difference of the scale

the smaller difference of the relief. There is a strong relationship between the relief and the terrain factors of the experimental area such as the average elevation

the elevation difference

the average slope and the average slope variability. Based on this

we build the prediction model of the relief. We use the prediction model to estimate the scale of optimum statistical unit and the accuracy of the prediction model to fitted parameter is above 95% . The experimental results show that the model can effectively determine the optimum statistical unit of relief.