A new approach of audio watermarking by use of phase retrieval algorithm and digital holography is proposed. The watermarking image is transformed into virtual object wave after phase retrieval algorithm. It interferes with the reference wave to form high contrast Fourier-transformed digital hologram. And the hologram is embedded into audio signal by quantification process and discrete-cosine-transform.The watermark can be extracted without the original audio signal and the security key provides a good security. Numerical experiments show that the algorithm is robust against common signal manipulations and attacks,such as lossy compression,re-sampling,low pass filter,noise,and so on.