In the present paper, the authors used the time-resolved coherent anti-Stokes Raman scattering (CARS) spectroscopy based on supercontinuum developed by ourselves to acquire simultaneously the molecular vibration spectrum and vibrational dephasing time of the molecular various vibrational modes. Using benzonitrile as the sample, the authors measured its vibrational relaxation processes at its five typical vibrational modes and obtained their vibrational dephasing time respectively. In the experiment, the authors also found the phenomenon that oscillations appear in the vibrational dephasing of plane bending vibration mode of benzene ring in benzonitrile, which was caused by superposition of the two adjacent normal vibrational modes excited simultaneously. After mixing benzonitrile with anhydrous ethanol, the authors also measured their vibrational dephasing time. This method is capable of monitoring the changes of the molecular characteristics and its micro-environment, therefore it will find widespread applications in biology, chemistry and materials science.