A new method to suppress the zero-order image by processing digital hologram with Gaussian kernel function in spatial domain is proposed.First，an original hologram is filtered by Gaussian kernel function.Then，the original hologram decreases the filtered hologram to suppress the zero-order image. It is correct and effective to suppress the zero-order image by experiment.Compared with the methods of the hologram subtracts its mean，the hologram subtracts its local mean and frequency domain，the new method has a better and faster effect.The proposed method improves the quality of digital off-axis holography reconstructed image.