The velocity fluctuation of the interferometer is one of the important factors affecting the spectral signal-to-noise ratio.To further improve the spectral signal-to-noise ratio ,the relationship between the velocity fluctuation of the interferometer and the spectral signal-to-noise ratio is studied.In th is paper,the causes of optical path difference velocity fluctuation of the tilt compensation interferometer are quantitatively analyzed from the aspects of rotation angle, velocity feedback testing,and circuit noise.On this basis,the influence law of optical path difference velocity instability on the spectral signal-to-noise ratio is verified through theoreti cal analysis and experiments.The experimental results show that in the same wavenumber range,the higher the velocity stabilit y of optical path difference,the better the spectral signal-to-noise ratio.When the velocity stability is increased by 5% ,the spectral signal-to-noise ratio is increased by about 14%—16%.When the optical path difference velocity is constant,the spe ctral signal-to-noise ratio in the low wavenumber band is significantly better than that in the high wavenumber band,a nd the signal-to-noise ratio in the 2100—2200cm－1 band is about 20% h igher than that in the 2500—2600cm－ 1 band.The research results provide a theoretical basis for the design of a high signal-to-noise ratio spectrometer.