The cavity field spectra for the nondegenerate two-photon Jayners-Cummings model with an additional Kerr-like medium were investigated. The results of the initial fields in pure number states were presented, and effects of self-phase modulation on the spectra structure were analyzed. It is found that the cavity field spectra are generally in two-peak structure for each mode. With the increase of the self-phase modulation effect of one mode, the peak-space of this mode get a raise and one peak rises and the other peak reduces for the both mode spectrum.