A light holographic watermarking algorithm based on CMYK color space was put forward based on CMYK color space, Fourier hologram encryption, and digital watermarking theory. The algorithm without color space conversion avoids losing watermark before printing and improving the similarity of the reconstructed watermark; due to the characteristics of the Fourier transform, overlaying the conjugate image of the reconstructed watermark and the original watermark image can increase definition of reconstructed watermark when decrypted. Experimental results showed that the algorithm has good invisibility and strong robustness and is able to resist general image processing operations.