In this paper, we study the chaotic behavior of a two-photon quantum optical model. The results show that the model can exhibit chaotic behavior without any perturbation or modulation terms. The chaos is characterized by Fourier analysis and the maximal Lyapunov exponent. The properties of the chaotic behavior are also discussed. We proved that the two-photon J-C model, which contains the rotating-wave approximation, cannot exhibit chaotic behavior.