Abstract: For having the copyright security of the digital audio frequency product，this article proposes a blind digital audio watermarking algorithm in complex cepstrum domain based on the chaotic encrypting and repeatencode modulating.The audio signal is divided into several frames which include the same samples and the frame is transformed with complex cepstrum.Then taking a binary image which having the message of copyright as watermark，the chaotic sequence encrypts it and the repeatencode can be embedded into the complex cepstrum coefficients after rectifying error while the watermark can be extracted without the original audio signal.By doing this，blind detection of the watermark is achieved.Experimental result demonstrates that the algorithm is of much robustness and imperceptibility and thus can endure processing and attacks from common signals，such as resampling，extra-noise，low-pass filter，remodulation and audio frequency format conversion etc.