The invention relates to a wavelet coefficient adjustment watermarking method based on modular operation. The method integrating wavelet and SVD comprises steps of firstly, according to different features of information carried by a carrier image, selecting a smooth area with small pixel point dynamic range change for secondary wavelet transformation, carrying out singular value decomposition ona corresponding wavelet coefficient, and reducing the coefficient change amplitude by using modular operation to realize watermark embedding for the problem of poor image robustness caused by large image coefficient change of the conventional SVD. According to the method, the quality of the image and the robustness of the watermark are improved, the robustness on common signal processing and geometric attacks is very high, and the effect in the aspect of resisting rotation attacks is particularly outstanding.