Herein, using a spectral broadening evolution testing setup, the relationship between the polarization-extinction ratio (PER) of the photonic crystal fiber (PCF) output light and spectral broadening evolution is observed. By measuring, comparing, and analyzing the lifetimes of the three tapered PCFs, we find that the tapered PCFs experience four-photon absorption processes at the pump light wavelength. The reason for the spectral broadening performance degradation of the tapered PCF is that the multiphoton absorption in the fiber core results in the color-center defect. A light source with low photon energy is proposed to reduce the multiphoton absorption. The experiment verifies that using the pump light with wavelength of 1040 nm can effectively prolong the spectral broadening lifetime of the tapered PCF.