Abstract: Through numerical simulation based on the particle flow method, DEM numerical test samples are generated in accordance with the results of laboratory tests on standard sand. Using gravity deposition modelling of irregular sand particles, samples of biaxial test assembled by long particle units are generated. Different steps of deposition are applied during the process of generating samples in order to simulate different inherent states of samples. The loads from the horizontal and vertical directions are respectively applied to samples. The numerical experimental results show that the gravitational deposits have significant impact on the major axis orientation arrangement of particles and the average coordination number. Also, there is a change in the macroscopic stress-strain curve and mechanical parameters acquired from the results of applying loads to the samples from the horizontal and vertical directions. The tested sand samples exhibit inherent mechanical anisotropy, which is closely associated with the internal structure properties and microscopic mechanical properties of sand.