This paper presents an improved patchwork method in wavelet domain for digital audio watermarking. Two special subsets of the host signal features were selected to embed the watermark signal, adding a small constant value to one subset and subtracting the same to another patch. The method is based on wavelet domain and the watermark signals were embedded in approximation coefficients. In order to control the inaudibility of watermark insertion we try to use various constant values and select the optimal one to guarantee a desired quality for the watermarked audio signal. The quality of the watermarked signal is evaluated by PSNR (Peak Signal Noise Ratio) method and Extract Ratio(ER) after various attacks. Simulation results show that the proposed method is robust against various common attacks such as filtering, resample and so on.