Abstract: The acoustic propagation model Kraken can calculate the normal mode in the range-independent environment and the parabolic model Ram has the ability to compute the sound field in the range-dependent ocean environment. A parabolic equation algorithm with normal solution as the initial field is proposed in this paper. This method uses the normal mode method Kraken to calculate the single or multiple normal modes as the parabolic model's initial field and calculate the energy distribution and propagation characteristics of arbitrary normal mode in the arbitrary ocean environment, so as to analyze the normal mode coupling. Besides, this method can not only overcome the low frequency limitation of coupling model, but also upgrade the computational efficiency with high accuracy. It can be used as a general model for high or low frequency acoustic propagation in shallow sea or deep sea.