In order to solve the problem of complex and time-consumption of reference signal zero crossings in the traditional "Brault" sampling method, a method based on Fourier interpolation technique was proposed to find the zero-crossing. Compared with other interpolation methods, the results showed that this method could ensure the accuracy of zero-crossing information and simplify the complexity of data processing. The linear fitting coefficient of zero-crossing information obtained was greater than 0.999. In the range of 2 100-2 200 cm-1, when the error of reference laser signal was small, the instrumental SNR obtained by the Fourier interpolation method was 1.03 times that obtained by the cubic spline interpolation method, and the result obtained by the linear interpolation method was consistent with Fourier interpolation method. When the error of reference laser signal was relatively large, the instrumental SNR obtained by the Fourier interpolation method was 1.05 times of the SNR obtained by the linear interpolation method.