Based on the Peierls-Hubbard Hamiltonian, the influence of electron-phonon inte-raction on the spin excitation of itinerant electron system has been analysed. It is shown that the interaction not only changes the dynamic property of －＋（ｑ，ω），but also causes the gap between two spin subbands to become narrow, which makes the electron-hole pairs easy to be excited singly. It should be emphasized that the spin excitation spectrum has an energy gap duo to the presence of above-mentioned electron-phonon interaction.