Abstract: In this paper the two-way parabolic equation (2WPE) is used to predict the propagation characteristics of electromagnetic waves in complex sea environments, and the two-way finite-difference(2WFD) method is used to solve the 2WPE. The effects of backward electromagnetic waves caused by irregular terrain such as islands and the influence of atmospheric duct on electromagnetic waves are considered. An improved fractal sea surface model is introduced in the prediction of forward and backward wave propagation to simulate the actual sea surface boundary. This model can simulate characteristics of the large-scale surge and capillary of the sea surface. The two way propagation factors calculated by improved fractal sea surface model are compared with those calculated by the Miller-Brown model. The numerical simulation results show that under the same wind speed condition, the two-dimensional electric wave propagation factor calculated by using the improved fractal model to deal with the sea surface boundary is more severe, which can more accurately reflect the influence of the actual undulating sea on the electromagnetic wave propagation.