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 this 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 theoretical analysis and experiments.The experimental results show that in the same wavenumber range,the higher the velocity stability 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 spectral signal-to-noise ratio in the low wavenumber band is significantly better than that in the high wavenumber band,and the signal-to-noise ratio in the 2 100—2 〖ＫＧ－１／６〗200 cm－1 band is about 20% higher than that in the 2 500—2 600 cm－1 band.The research results provide a theoretical basis for the design of a high signal-to-noise ratio spectrometer.