The energy levels of magnetopolaron in the wurtzite GaN/Al0.3Ga0.7N quantum well structure are studied by using Lee-Low-Pines (LLP) variational method. The ground state energy in wurtzite GaN/Al0.3Ga0.7N quantum well structure is calculated as a function of well width L and external magnetic field B. The transition energy and cyclotron frequency of magnetopolarons are calculated as functions of magnetic field B. The anisotropy of the optical phonon modes and the interaction of electron-optical phonon in wurtzite GaN/Al0.3Ga0.7N quantum well are considered in numerical calculation. For the qualitative analysis and comparison, the energy and cyclotron frequency of magnetopolaron in zinc blende GaN/Al0.3Ga0.7N quantum well are calculated.