Abstract: This paper studies the generation and transmission characteristics of leakage sound waves of gas pipeline, analyzes the generation forms of leakage sound waves, and obtains the time domain, frequency domain and time frequency characteristics of sound wave signals. The study results show that the leakage sound waves are mainly caused by the monopole, dipole and quadrupole source generated by interaction between transfer medium and pipeline, primarily reflected by energy catastrophe, but the occupied time domain is narrow, and occupied frequency domain is wide, and main energies are centralized at 0~100 Hz. In the research, the authors carry out the simulation study on the transmission characteristics of leakage sound waves in special fittings (elbows, reducers, branches), and perform the experimental study on leakage devices of high-pressure gas pipeline, and analyze the transmission law of leakage sound waves and determine the main factors impacting sound wave signal attenuation. Results show that the sound waves are transmitted in plane waves in pipeline, and the sound wave is basically attenuated in exponential law with the increase of transmission distance, if it has small leaking quantity, the leakage sound wave signal amplitude will basically has relation free with size of leakage hole; the loss of sound wave signal after passing through elbow and straight pipes are basically zero, and the loss after passing through branches and reducers is greater. According to the results of fitting calculation, the theoretical installation distance of existing type sound wave sensors can be up to 100 km, favorable for leakage detection of long-distance pipeline.