The characteristics of acoustic signal for pipe leakage and general wavelet primary function were analyzed. It concludes that the suitable primary functions for acoustic signal of pipe leakage are Daubechies wavelet and Symlet wavelet. The experiments of the acoustic inspection were conducted in water leakage of the carbon steel pipe and the wavelet transform of the leakage signal was done by db5 and sym5 wavelet. It shows that the most energy is a6 level signal energy and the peak frequency of the signal focus on 2.90~3.81 kHz. The maximum relative error of two different wavelet transforms is 0.77% in the energy analysis and 5.17% in frequency analysis.