The dynamics of the two_photon Jaynes_Cummings model with atomic motion are studied by using the quantum information theory, and the quantum echanical channel representing the state change of atom is given; the quantum mutual entropy and reduced entropy of the atom are derived. The influences of the atomic motion and the field structure on the quantum mutual entropy are examined. It is shown that the properties of quantum mechanical channel are strongly dependent on the atomic motion, the field model structure, and the entanglement between the atom and the field.