The effect of external vibration on the velocity uniformity of the moving mechanism of the angular mirror translational Fourier transform interferometer (hereinafter referred to as interferometer) can be quantitatively analysed by the interferometer optical range difference velocity stability. The article proposes a more comprehensive method of analysing the optical range difference velocity uniformity for the reliability of the interferometer kinematic mechanism under the influence of on-orbit microvibration in the process of space spectroscopy detection. The method incorporates the structural response of the interferometer caused by external excitation into the stability analysis as one of the influencing factors, so as to reflect the reliability of the interferometer in orbit more realistically, and judge the microvibration criticality that the interferometer can withstand more accurately. At the same time, an optical surface model of the interferometer is established to further theoretically characterise the effect of microvibration on the homogeneity of the interferometric mechanism. The method discussed in the article provides a way of thinking for the judgement of the reliability of the mechanism movement under the external excitation perturbation as well as the research on the optimisation of the mechanism control.