The excitation function and isospin dependencies of σR have been investigated by using the Boltzmann-Uehling-Uhlenbeck (BUU) model with a square-type density distribution. When the width parameter of the square distribution is obtained by fitting σR at relativistic energies, the BUU-model can reproduce the experimental data at intermediate energies better than Glauber model. The systematical underestimation of σR at intermediate energy by Glauber model was removed out now by BUU calculation framework. It is also found that σR is sensitive to nuclear equation of state and σin- NN medium. The difference factor d defined in text is sensitive to the nuclear structure such as neutron halo and neutron skin, etc.