In this paper, a color image sharpening method based on fractional differentiation and discrete cosine transform (DCT) is presented. First, the definition of fractional differentiation is reviewed briefly. Then, the DCT, fractional differentiation and Mach band effect are used to construct the color image sharpening algorithm. Next, the extension work of the proposed method is discussed. Finally, some numerical examples are demonstrated to show the effectiveness of the proposed digital color image sharpening method.