In a quantitative Ground Penetrating Radar (GPR) data processing, it is necessary to determine three principal parameters: depth, position, and size of the buried objects. However, this process takes too much time because of the complex calculus stages such as: data formation, topographic correction, data filtering, amplification and some others. In addition, the determination of those parameters for buried objects using traditional GPR methods has many difficulties since this estimation depends directly on electromagnetic wave velocity in the material, and this velocity varies very complex in all directions. Especially, for close buried objects, they always superimpose upon each other not only in the spatial domain but also in the frequency domain, making the identification for these objects significantly problematic. In this paper, the wavelet transform modulus maxima (WTMM) with the selective wavelet functions are introduced to process the GPR data, thereby it is easy to estimate the depth, size and position of the buried objects without the consideration of the electromagnetic wave velocity in the material. This GPR analysis can be applied for designing and mapping urban underground construction works.