根据图像数字水印基本原理和水印信道的构造及生成方式，从信息论的角度，对基于高斯噪声信道的数字水印容量进行探索。针对高斯信源分布具有最大的不确定性、能够在所有的二阶随机分布中提供最大信息熵的特点，分析在高斯分布情况下的整个水印信道通信过程，并引入平均互信息理论，给出基于高斯的水印信道容量的最大通信速率。同时分析加性噪声信道下的容量问题，将高斯分布扩展到非高斯分布，优化容量计算表达式，利用Matlab软件工具给出非高斯信源水印容量与受限失真度的2D和3D关系仿真曲线，并结合实际给出结果分析。-】Based on the digital watermark and information theory, a rudimental research for the Gaussian watermark capacity is given. Considering that Gaussian distribution has the maximum uncertainty with the maximum entropy among all given second-order distributions, this paper focuses on the watermark communication process with Gaussian channel, and uses the average mutual information to analyze the communication capacity. Also the additive noise channel is introduced to expand the non-Gaussian case. The formula of maximum transmission rate for Gaussian watermark channels is given and simplified, and the 2D and 3D curves for the relationship between the distortion and channel capacity by Matlab are illustrated. It analyses the results at different distortions in two different usages of watermark.