The CAES spectra of v1 and v8 vibrational modes of silane (SiH4) have been measured and analyzed. By means of the polarization CAKS technique, the spectrum of v8 band is separated from that of v1 band and so the CARS spectrum of pure v3 band has been obtained. The frequency shift between the Q-branoh peaks at v1 and v8 as well as the ratio of their Hainan cross-sections square have been determined from polarization CAES spectrum and by computer simulation.