To accurately locate the leak in the buried gas pipes, accelerometers are mounted on the ground to detect the leak-induced vibroacoustic waves. A new method using nonuniform L-shape array is proposed to jointly estimate the 3D coordinate and wave-speed. A small-aperture L-shape subarray is embedded into the large-aperture L-shape array and is combined with the Root-MUSIC algorithm to find the relationship between DOA of far-field source and wave-speed. Then, the large-aperture L-shape array is used to perform 2D spatial spectrum estimation for wave-speed and near-field source distance. Finally, the 3D coordinate is calculated using the estimation results and the computational complexity is reduced. The results of localization experiments show a superiority performance of the used L-shaped array. The joint estimation method based on the L-shaped array can estimate the propagation speeds of leak-induced vibroacoustic waves in multiple soil conditions and the 3D coordinate of leak source is derived. Compared with the localization method using theoretical wave-speeds, the error in joint estimation method is reduced by 90. 9% , which avoids the influence of error in theoretical wave-speed on localization. Compared with the direct 3D spatial spectrum estimation, the calculation time of the joint estimation method is reduced by 88% and the localization accuracy remains well. The range of signal source, rmin ~ rmax, is calculated by using the far-and near-filed criteria. Experiments evaluate that accurate localization can be achieved within this range.