Abstract: A digital watermarking scheme is proposed in this paper, which is based on Independent Component Analysis (ICA) and able to resist copy attack effectively. In this algorithm, both the image signature describing the original image uniquely and the watermark are embedded into the original image synchronously and extracted through ICA techniques. By comparing the re-calculated signature of the marked image according to the image signature algorithm with the extracted one, the legality of the marked image can be determined and the purpose of resistance to copy attack can also be realized. Simulation results demonstrate the robustness and validity of this proposed method.