In order to study the fundamentals of leak detection and location for natural gas pipelines based on acoustic method, the propagation model of leakage acoustic waves is established and modified. First, the wave equations of leakage acoustic waves are researched in theory and the propagation law in actual pipelines is analyzed to obtain the damping impact factors which cause the attenuation. Then, the fundamental characteristics of leakage acoustic waves are obtained through experiments by time-domain, frequency-domain and joint time-frequency-domain analyses. Third, the actual propagation model is established which can be used to calculate the installation distance of the acoustic sensors. Finally, a new leak detection and location method is proposed based on the propagation law which is validated by the field experiments and the fundamental, the steps and the merits of the method are concluded. The results indicate: the propagation model can be established and modified by the experimental method combined with theoretical method, which can direct the acoustic sensors to be installed into the pipelines; the propagation-characteristics-based leak location method is effective. Conclusions can be drawn that the modified propagation model can make acoustic leak detection method used in natural gas pipelines better. (C) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.