Abstract: 6 sand samples are made by use of Fujian standard sand, Hangzhou sand and man-made quartz sand, respectively, with each sample composed of the single sand particle in diameter. The average particle roughness of every sample and the shear wave velocities (Vs) of each sample in different porosities are obtained by electron microscope and bender element testing equipment. The analytic results indicate that Vs is greatly influenced by the particle roughness, and the magnitude of Vs decreases with the increase of the particle roughness. The roughness coefficient is introduced to deduce the formula of Vs by means of the researches on micro fabrics and constitutive relations of granular materials, elastic contact of rough particles, etc. Moreover, the results drawn from the present method are compared with the measured data, and the calculating method of the roughness coefficient for low sands is obtained. In addition, the relationship between the roughness coefficient and the stress is discussed.