Abstract:An improved new method for watermarking technology based on discrete cosine transform technology is proposed in concern of its poor robustness. The new method takes use of the average value of high frequency band coefficients in discrete cosine transform approaching zero as its characteristic, combined digital watermarking with disorder permutation method as the preprocessing. The results testified improved discrete cosine transform can not only retrieve the digital watermark with better performance, and the image from which the watermark was retrieved nearly in perfect condition, shows better robustness.