作为信息隐藏的重要分支，数字水印是一种有效的数字产品版权保护和数据安全维护技术。近年来数字水印技术成为了信息安全领域的研究热点，也得到了较大的发展。基于变换域的水印技术是目前研究的热点和重点。本文系统介绍了数字水印的原理和应用方法，概要介绍了数字水印的几种主流算法，并重点研究了一种基于离散余弦变换(DCT)数字图像水印算法，并借助 MATLAB编程工具，实现数字水印的嵌入和提取仿真，以及为测试鲁棒性而对水印图像进行攻击实验。-As an important branch of information hiding, digital watermarking is an effective copyright protection of digital products and data security maintenance technology. In recent years, digital watermarking has become a hot research field of information security, has also been considerable development. Transform domain watermarking technique based on the current research focus and focus. This system describes the principles and applications of digital watermarking methods, an overview of several mainstream digital watermarking algorithms, and focus on a discrete cosine transform (DCT) digital image watermarking, and with the MATLAB programming tools, digital watermark embedding and extraction simulation, as well as test the robustness of the watermark image on the attack experiments.