A set of digital image processing algorithms based on multi-scale transform is proposed according to the characteristics of 3-D digital holography. By applying multi-scale principle of wavelet transform and curvelet transform,the zero-order diffraction spot is eliminated,and the speckle noise is reduced effectively while more edge information of object is maintained. As a result,the better quality image is obtained by combining the curvelet transform and digital holography. The experimental result shows that the method is practical and efficient.