The influence of the motion of atomic mass centre, field mode structure and initial mean photon number on the field entropy squeezing is investigated by means of the theory of quantum information entropy. It is shown that the motion of atomic mass center leads to the periodic evolution of the field entropy squeezing and this period depends on the field mode structure parameter;an increase in field-mode structure parameter results in not only shortening of the evolution period of the field entropy squeezing but also prolonging of the squeezing time;the field may exhibit long time entropy squeezing effect for some choieed system parameters.