Abstarct: Determination of geomechanical parameters is critically important due to their vital role in wellbore stability analysis, hydraulic fracturing, casing point selection, flow rate detection, etc. There have been many methods proposed to determine geomechanical parameters in which recent studies are concentrated on determination of these parameters under anisotropic condition. This might be due to accurate results obtained through taking the effect of anisotropy into consideration. However, almost all of the studies carried out on this topic are restricted to the well logs data where due to limited interval of data acquisition, generalization of results to other locations in the field is barely possible. Although there have been studies on the applications of VSP and seismic reflection data, the presented results were very unreliable and rather narrow. In this study a methodology is presented to use seismic reflection data to determine geomechanical parameters under Transverse Isotropy (TI) condition. Well logs and VSP data were used to calibrate and validate the results as well. Using the well logs data, it was revealed that how geomechanical parameters are related to compressional and shear wave velocities. In fact, by constructing a Mechanical Earth Model (MEM), safe mud weight window (MWW) was determined using three different failure criteria. A new methodology to determine safe MWW has then been presented according to extensive studies on the wellbores drilled in Iran and Australia. MEM was constructed in the next step through the use of VSP data. This process was initiated by prestack seismic data processing and followed by a new strategy to determine geomechanical parameters under anisotropic condition. It was also shown that how Uniaxial Compressive Strength (UCS) and in-situ stresses can be determined under anisotropic condition. At the end, seismic reflection data belonging to the Norowz oil field in south of Iran was processed and shown that how Thomsen’s anisotropy parameters together with Normal Move-out velocity can be used to determine rock stiffness parameters. In addition, due to important role of shear wave velocity in accurate determination of geomechanical parameters, two separate studies were done using Hilbert transform and seismic attributes to show how these methods can be successfully used to determine shear wave velocity