The fourth order coherence function theory has been applyed to study the nonlinear effects of fifth order on polarization beats of a cascade three level system in chaos field.By analyzed the cases that pump beams have either narrowband or broadband linewidth,we found that for both cases the beat signal of the different temporal behavior depends on the stochastic properties of the lasers and transverse relaxation rate of the transition.We also found that a Doppler free precision can be achieved in the measurement of the energy level difference.The spatial modulation behavior of the beat signal has also been discussed.