Making use of the molecular clceed-orbit theory and a new model potential for the Rydberg molecule,we have calculated the recurrence spectra of He2+ molecular ion in a magnetic field for different quantum defects.The Fourier transform spectra of He2+ molecular ion may be used to perform a direct comparison between peaks in the spectra and the scaled action values of closed orbits of the excited electron in exteal fields.We find that the spectral modulations can be analysed in terms of the scattering of the excited electron on the molecular core.Unlike the case of the Rydberg atom where the elastic scattering is predominant,modulations produced by inelastic scattering are also vital to the photoabsorption spectrum of the Rydberg molecule.Our results are in good agreement with the quantum results,which suggests that our method is correct.