To improve the performance of Fourier transform spectrometer,a high-precision velocity information acquisition scheme based on equivalent clock method is designed.The laser signal forms an interference signal through the interferometer,which is amplified,filtered and shaped into a pulse signal recognized by the digital circuit.Based on the mathematical principle of velocity information acquisition,the error of obtaining velocity information based on T method is analyzed,and the velocity information acquisition method based on equivalent clock method is proposed.After reading the pulse signal,field programmable gate array (FPGA) calculates the optical path difference velocity value according to the equivalent clock method.Simulation analysis and experimental results show that when the frequency of He-Ne laser interference signal is 9 kHz,the measurement error of velocity feedback based on equivalent clock method is only 0.01%,and high precision optical path difference velocity information acquisition is realized.This is of great significance to improve the control accuracy of the interferometer system and the signal-to-noise ratio of the spectrum.