Abstract: Quantum image watermarking algorithm is a typical issue of quantum image processing. At present, the domestic and foreign literatures are relatively small, and mostly for the monochrome images. In this paper, a typical quantum image watermarking algorithm based on quantum Fourier transformation is analyzed, and the improvement measures are put forward. These improvements include three aspects. Firstly, an improved quantum image representation is proposed, which extends the monochrome image to the color one. Secondly, the size of the watermark image is increased to the same as the carrier image. Thirdly, the quantum strategy of watermark embedding and extraction is given. The validity and feasibility of the proposed method is verified by the simulation results on a classical computer.