A novel method for the measurement of the polarization states of fiber distributed feedback (DFB) laser is proposed, which is based on stimulated Brillouin scattering (SBS) amplification effect in optical fibers. Based on the interaction of the outputs of a tunable laser source (TLS) and a DFB laser, the absolute wavelengths of the double polarization states, the relative wavelength interval and respective light power of the laser are obtained. The influence of lateral pressure to the DFB laser is studied, and the single-polarization single-mode output is realized. Compared with the method using Fabry-Perot (FP) etalon, FP interferometer and heterodyning in previous studies, this method is easier to operate and can acquire more informations about the polarization states.