In this article, watermarking algorithm is studied using digital watermarking technology based on the discrete wavelet (DWT) multi-resolution decomposition algorithm. Three-level wavelet decomposition is employed so that images are divided into three serial sub-graphs with high frequency band and one sub-graph with low frequency band. Since low-frequency information is more sensitive to human eyes than high-frequency information, watermarking is embedded into the high-frequency coefficients of the wavelet image. In our experiment, watermarking information is embedded into the original images by Matlab simulation. Besides, salt and pepper noise, Gaussian low-pass filter, amplifying 200% after narrowing 50% attack as well as JPEG coding are used to test the algorithm. Results show that our algorithm is robust and the visual effect is satisfactory.