The anisotropic property of sedimentary rocks are influenced by geological processes such as sedimentation pattern, grain size and grain sorting, hence it might be a significant impact to the seismic wave propagation. An identifying method of the anisotropic property is done by deriving the relationship between group velocity and phase velocity of a P-wave seismic diffraction function. Subject to be studied are Naintupo Formation, Tabul Formation and Tarakan Formation which are lied in Tarakan Basin, these formations are an anisotropic sedimentation products, generally composed of sandstone and shalestone by thickness more than 1000 meters. In the seismic section, it is shown by range of 1500 msec - 3000 msec. The diffraction function observed at a point of the diffractor due to the normal fault. There are 3 points of observation, SP.1374, SP.1375 and SP. 1376 which assign anisotropic value δ and ϵ, where the δ value is in the range of 0.26 - 0.28 and the ϵ value is in the range of 0.46 - 0.72, picked from 42 samples. Furthermore, Pre Stack Depth Migration was carried out through 2 velocity models; there are velocity model with anisotropic parameters δ and ϵ derived from diffraction functions and the constrained velocity inversion method. After the curved ray pre-stack migration process, it is found that the velocity Vp (900) of diffraction method faster than the constrained velocity inversion method, where the δ value for both methods are 0.35 but the ϵ for the diffraction method is 0.4 and the constrained velocity inversion method is 0.35. Regarding to the result of the 2D NW-SE PSDM stack, there is a more obvious fault compartment observed from the diffraction method.