Abstract: Considering the limitations of circular particle simulation,the elliptical particle element was developed by using the clump logic in particle flow code.The effect of particle shape on the macro-mechanical behaviors of numerical samples under monotonic shear loading was studied,and the mechanism was explained microscopically.The evolution of average co-ordination number during the process of loading was particularly investigated,and the influence of particle shape on the critical average co-ordination number was also evaluated.The particle rotation property was compared between the elliptical particle samples and the circular particle samples,and the development of fabric anisotropy during loading was also analyzed.It was found that the strength and the deformation properties of numerical samples were obviously affected by the particle shape and the mechanism was microscopically related to the average co-ordination number.During the process of loading,there was a tendency of the long axes of elliptical particles to align in horizontal direction,and the contact normal gradually oriented in the direction of the major principal stress.