Abstract: Hologram stitching technology was used in phase-shifting interferometry to improve the quality of reconstructed image. By using the principle of correlation, the sub-interferograms captured by CCD were stitched into an integrated hologram. And the stitched hologram was reconstructed by standard four-step phase shifting interferometry algorithm to restore the object light. For the sake of comparison, the same reconstruction operation was conducted on the original sub-interferograms without stitching. Computer simulation experiments verified that the image quality could be improved obviously by this stitching technology. In addition, holograms were processed by zero padding and stitching, and the results showed that the zero padding could only improve the detail displaying ability, while the stitching technology improving both the resolution of reconstructed image and field of view.