Abstarct: The study of complex structures is of great importance in the detection of hydrocarbon reservoirs. Since the presence of fluids in complex structures causes significant changes in the elastic properties of the earth, it is possible to reconstruct the elastic parameters in such structures using seismic imaging methods and then reach to the precious exploration resources. Complex structures are those structures that are difficult to reconstruct or cannot be reconstructed using conventional imaging methods due structural complexity or complexity in the velocity model. The more the complexity of the structure, the more difficult it would be to image because of the increased complexity of simulating wave propagation. In the meantime, the study of the near-surface complex structure in which the surface and the body waves are present together has a huge computational cost and challenges when solving problems. Formerly, the traditional surface wave analysis methods with estimation of the shear wave velocity were used to 1D model near-surface structures. Such methods are weak in modeling structures with velocity contrast and extreme lateral velocity changes. Today, full waveform inversion (FWI), which uses body and surface waves to reconstruct the elastic parameters of the Earth, is an appropriate alternative for 2D modeling of near-surface complex structures. Seismic attenuation parameter also plays an important role in subsurface characteristics. This parameter mainly affects the amplitude of the seismic wave and also affects the phase of the seismic wave if it is strong. Consideration of the attenuation effect is also becoming an important issue in FWI studies. In the presented study, the multi-parameter quasi-viscoelastic full waveform inversion in the time domain is used to reconstruct the elastic parameters of the earth (P-wave velocity, S-wave velocity and density) of a shallow synthetic model with dimensions of 50 meters in the horizontal direction and depth of 20 meters, which has a complex geometric structure. In the forward modeling process, the viscoelastic wave equation is solved using the finite difference method considering the appropriate initial and boundary conditions. The generalized standard linear solid model with an almost constant priory estimated quality factor using the relaxation time of P and S waves is used to describe the rheology of the medium. The conjugate gradient method is used to solve the inverse problem with a multiscale approach. The problem is solved in a period of approximately 10 hours with a computer which has eight cores with a speed of 1.3 GHz and 16 GB of RAM. If the P and S wave’s velocity values are not high, the reconstruction of the model parameters is done using low frequency content seismic data and a mechanical seismic source would be enough to generate the seismic data. On the contrary, when the velocity values are increased, the model parameters, especially the P-wave velocity, cannot be reconstructed using low-frequency content data, and a vibroseis source must be used to generate data with high-frequency content. The results of the research showed that the reconstruction of the model parameters in case of using both low frequency content data and high frequency content data is satisfactory and the S-wave velocity is inverted with higher resolution than the other two parameters which is due to the presence of surface waves in the inversion and the longer P-wavelength compared to the S- wavelength.