Aero-dynamic and mechanical properties such as terminal velocity, Reynold's No., drag coefficient, coefficient of friction, repose angle and seeds hardness for three different oil producing crops (sunflower, soybean and canola) were determined at five different levels of seeds moisture content; while, shear force and shear stress of soybean hulls and cotyledons were also determined at the proper moisture content for oil extraction. The obtained results show that, for aerodynamic properties, both of terminal velocity and Reynold's Number of all studied crops increased linearly with the increase of seeds moisture content. While, drag coefficient decreased with the increase of terminal velocity. However, coefficient of friction was varied with seeds moisture content and type of friction surface. Also, it was increased with the increase of seeds moisture content. Meanwhile, stainless steel surface recorded the lowest values of friction coefficient whereas the rubber surface recorded the highest values. Also, the angle of repose increased with the increasing of moisture content. While, seed hardness decreased with the increase of moisture content. However, both of shear force and shear stress of soybean hulls and cotyledons were higher in the longitudinal direction as compared with the lateral direction. Mathematical relationships were also developed for the different studied crops to relate the change in seeds moisture content with the obtained values of all aero-dynamics and mechanical properties.