The granular dynamic shear strength is the same as that of the staatic one in nature, as found from munerous experiments and investigations. The shear strength is equal to the sum of the interanl frictional rorce and the cohesive force. The influences of type, shape, size distriburion, proe ratio, moisture content and variation of vibration velocity on the dynamic shear strength of granules were stuied. Based on numerous vibration shear experiments, the authors investigate the mechanism of dynamic shear strength in granules in etrms of the fundamental principle and the relevant theory of modem tribology.