Speckle noise is often obvious in the reconstruction of object image by digital off-axis hologram.In this paper,speckle denoising is realized by reducing the coherence.The interferometric recording is realized by arbitrary polarized object light and linear polarized reference light.The speckle noise produced in digital holography can be effectively reduced by averaging these light fields.By controlling the rotation of three wave plates to realize arbitrary polarization state,the holograms of different polarization states are obtained.The speckle contrast of reconstructed object images is different under different polarization states.The optimal results are obtained by comparing and analyzing each reconstructed image.The speckle noise in the reconstructed image is well suppressed and the effect is better than that in the single polarization state.The effectiveness of this method in suppressing speckle noise can be seen from the analysis of experimental results.