The evolutions of quantum information for atoms, field and system in Kerr medium and Raman interaction are discussed. The effects of intensity of light, detuning parameters and Kerr coefficients on the fidelity are studied. It is shown that the evolutions of fidelity exhibit oscillations with equi-amplitude and perfect periodicity if the frequency of Rabi oscillation is the linear function of the photon number. Increasing the intensity of light will decrease the fidelity, and increasing the detuning parameters will improve the fidelity. Kerr coefficient affects the fidelity slightly and irregularly. The fidelity oscillates with equi-amplitude and perfect periodicity in the case of Δ=0, χ=0.5g and Raman interaction for degenerate levels.