In this paper, the entropy properties of the field in the two-photon Jaynes-Cu-mmings model with an additional Kerr medium are studied, the effect of nonlineari-ty interaction of the Kerr medium with the model field on the field entropy are discussed. With the help of quantum interference in phase space between two part of the bifurcation of the Q function of the field, the physical mechanism of properties of the field entropy are explained.