Abstract: Super continuous spectrum phenomenon can appear when using femtosecond laser in the process of transparent materials.On the basis of the principle of supercontinuum generation, the experimental scheme of linear polarization and circular polarization and PMMA materials with different energies is designed in order to analyze the threshold of supercontinuum spectrum of PMMA material under different polarized lights.Supercontinuum spectra of two polarized states of linear polarization (TE and TM) and circular polarization under different energies are analyzed and compared with superconducting spectra of the same energy. In the experiment, femtosecond laser with the pulse width of 160 fs and center wavelength of 775 nm is used. Experimental results show that energy of the same polarization is wider and spectrum width is wider. By comparing spectral characteristics under different energies, threshold of the spectrum and the circularly polarized light is 0.46 μJ and 0.586 μJ respectively. The spectral width of the linear polarization is wider than that of the circular polarization and circularly polarized light.