The pipelines are a frugal and safe way to transport gasses, oil, and other petrochemical materials. Many problems may occur in pipelines while the leak is one of the most frequent problems and must be dealt with it. The present work has presented a simulation and practically analysis of underwater gas leak detection system. Numerically, the governing equations are discretized by a finite volume method by using a staggered (non-collocated) arrangement of the variables. The solutions are obtained using the SIMPLE algorithm with UDS and CDS. A microphone array has been implemented for leakage detection. Experimentally, the results are carried out for inlet air velocity range of 5,8,11 m/s for three pipes with a length of 1 m and diameter of 8mm at a different diameter of leak 2,4,8 mm. The results have been showed the matching between the simulation and practical measurement of the accuracy of the leak detection and location determination on these pipes at three levels of measurements, under, at, and over the water level with different flow rate