Abstract: The study of propagation prediction methods and characteristics of radio waves in evaporation duct environment over the sea is of paramount importance for the design and application of maritime wireless communication systems. To achieve accurate and efficient prediction of electromagnetic wave propagation in a 3D maritime evaporation ducting environment, this paper introduces a 3D parabolic equation radio wave propagation prediction model based on the reordered-alternate direction decomposition technique. By decomposing the diffraction term into three independent items, the model reduces the dimension of the solution space. Taking advantage of the commutative property of the Fourier transformation, the computational load of the step-forward direction is halved, thus significantly enhancing computational efficiency and facilitating efficient calculations for the 3D parabolic equation. Empirical results demonstrate that, compared to conventional 3D parabolic equation models, this model can maintain prediction accuracy while effectively reducing computational requirements. It increases computational speed and bolsters real-time prediction capabilities, especially over large-scale long-distance 3D maritime evaporation duct environment.