To break through the limit of attitude measurement accuracy of traditional star sensors，the interferometric angle measurement technology can be applied to star sensors.Based on the centroid positioning technology，the fringe phase movement can be obtained from the energy of image points，and then the incidence angle can be obtained.In this paper，the imaging mechanism and characteristics of interferometric star sensors are investigated based on Moiré fringes，the influence of the optical structure parameters on the imaging effect and errors are analyzed，and finally methods for reducing the errors are given.It is shown that the grating cannot completely suppress the diffraction light beyond the ±1 diffraction order，resulting in multiple sets of image points.Therefore，the grating period and detector distance should be adjusted to move other image points off the screen.Besides，the mismatch between the Moiré fringes and the system aperture will bring segmentation errors.Thus，the deviation between the Moiré fringe period and the system aperture should not exceed 0.5%，and the phase extraction error at this moment should not exceed 2%.Moreover，when the distance between two gratings is not in accordance with the Tabor distance，there will be a phase deviation in the imaging.In view of this，the reference wavelength should be designed according to the target spectra.