In this paper, the evolution of the occupation probability in the system of two two-level atoms interacting with a single mode light field in the Kerr medium is studied by C-RWA. The influences of Kerr effect and virtual photon field effect on the occupation probability are also discussed. It has been shown that the quantum noise appears under C-RWA;the quantum noise becomes weak while ω increases: the amplitude of Rabi oscillation decreases while g increases, and the occupation probability of initial state increases while μ increases.