Denoising operation is usually needed for obtaining the phase of optical field by optical interferometry, and current denoise algorithms can achieve good results when the phase of optical field changes slowly. If the phase has high spatial variation frequency, the conventional denoise algorithms often cause loss of phase detail and fringe breaks. For this reason, by introducing shearing of optical field to reduce the frequency significantly and separating the speckle noise from optical field, a new denoise algorithm and corresponding theoretical analysis are presented. The validity of this new algorithm is showed in one simulated result and one experimental example of denoising; and the obtained phase approaches experimental value well, proved that this new algorithm is better than conventional algorithms.