To improve the positioning accuracy of the leakage application of the direct buried hot water heating pipe network by acoustic method, based on the analysis of the applicability of various wavelet threshold functions, an improved threshold function noise reduction method is proposed. This method can theoretically overcome the constant deviation of the soft threshold function and the shortcomings of the hard threshold function signal oscillation. Through setting adjustment parameters, improving the noise reduction ability, and retaining the signal of the region less than the threshold point to avoid effective signal loss. The experiment was carried out in a large direct buried hot water circulation pipe network. The research showed that the leakage positioning error was within ±1 m and the positioning accuracy reached 0.11%~3.49%. Finally, the acoustic leakage detection method was adopted in a practical engineering case of a Beijing heating system. The leakage location error is 0.37%~0.66%, and the positioning accuracy has efficiently is improved.