The Hyper-spectral Infrared Atmospheric Sounder( HIRAS) is a new vertical temperature and humidity detection instrument carried by China ’s second-generation polar orbiting meteorological satellite FY-3D. The determination of the zero optical path difference( ZPD) position of in-terferograms is the premise of interferogram overlays. However, in practical applications, it is difficult to determine this position because of the influence of the instruments involved and their environments. In this study, based on measured on-orbit HIRAS data, the influence of ZPD position deviation on data inversion is analyzed. The maximum correlation method and the minimum imaginary part method of complex spectra are used to detect the ZPD position. After the correction, the phase difference between the inner blackbody and deep space is approximately π. The imaginary part of the calibrated spectra is nearly equal to 0, which only represents noise. This method can be well used for HIRAS data preprocessing.