Raman spectra of liquid carbon disulfide (CS) and carbon tetrachloride (CCl4) were measured. And the spectral intensity was analyzed using the J. F. Bertran theory and the group theory. The rule about Fermi resonance was obtained from the Raman spectra of carbon disulfide (CS) and carbon tetrachloride (CCl4),(1) The energy can transfer between a fundamental and an overtone frequency about Fermi resonance;the two spectra have the same intensity. The spectral intensity of the two spectra was equal (R=1) about Fermi resonance,when the difference between fundamental of Fermi resonance and overtone of Fermi resonance was very small. (2) The intensity of overtone is stronger than that of fundamental’s. (3) The spectrum of Fermi resonance was observed,but the fundamental frequency was not. This article has very good reference value for the assignments in the molecular structure and the research of contents.