In order to obtain unification between the robustness and invisibility of watermarking images, under the condition of the same quality of watermark, the more robustness of for anti-interference and noises in image processing can be obtained. Improved watermarking algorithm for color image based on quick block singular value decomposition is proposed. SVD transformation preserves both one-way and non-symmetric properties. This watermarking algorithm is purposed to embed the watermark by both of the U and D components of improved SVD. Experiments and attacks test show that the algorithm has good robustness. Furthermore, the extracted watermark can still be easily identified after tampering.