Abstract: Influenced by construction technology, quality and environment in the construction process of rock-fill concrete gravity dam, natural cementation sands may have different cementation strengths between the sand particles. By using the microscopic model BPM of PFC^3D, the distribution of the bond strength in cemented sand is defined as the normal distribution to study the mechanical properties of cemented soil with different bond strengths. The mechanical properties of cemented sands under different contents and variances are analyzed. The results show the strain softening and shear dilatation characteristics. And with the increase of cement contents, softening and dilatancy increase. When the deviatoric stress reaches the peak value, with the increase of the axial strain, the change of the volume is reduced by the shear contraction. The volumetric strain is changed from the shear shrinkage to dilatancy. With the assumption that the cementing of sample under the normal distribution cementation strength, the peak stress linearly grows with cement content, but charge of the normal distribution variances has a little influence on the cementation of strength.