<正> The cyclotron resonance of magnetopolaron in quantum well wires (QWWs) have been studied withthe use of variational solutions to the effective mass equation. The results show that both the abso-lute value of the electron-phonon interaction energy and the cyclotron resonance frequency de-crease with the increase of the sizes of QWWs, and also that the cyclotron resonance frequency in-creases with the external magnetic field.