On account of the changing of permittivity along with frequency, it is necessary that the dispersion of rough land and sea surface should be studied. Based on the study of dispersion of land surface, a novel model including the bound water is presented by comparing the dispersion of bound water with that of free water. The relationship between permittivity and frequency is studied, and the result shows that the model is more preferable than the Dobson's. On the other hand, a modified model for the permittivity of sea surface is presented by comparing the single and double Debye models in relaxation law. The dispersion of sea surface is studied, and the relaxation frequencies are analyzed at different temperature respectively. The results show that it is the second relaxation frequency that obviously expands the effective range of Debye model, which confirms the validity of the new model.