Sandstone is sediment rock composed of many cemented sand particles, and corresponding particle constraint and force bearing capacity are greatly controlled by the cemented property. In order to better reflect the cemented property influencing on the mechanical characteristics of the sandstone, take the oil sandstone reservoir for instance, a numerical model based on 3Dimensional Particle Flow Code (PFC3D) considering the parallel bond model was brought forward to simulate the failure mechanism during shearing process. The sandstone cemented property is modeled based on random mathematics and advanced development of Particle Flow Code (PFC), and the relation of the stress ratio, volume strain, coordination number and bond-broken number and the axial strain is analyzed in detail, especially the contact network evolution indicated the force chain is important to transfer the external force, which verifies the feasibility of the numerical model. Based on the above PFC3D model, a series of researches on changing the cemented radius ratio, parallel bond stiffness and cemented volume of the particles have been done to clearly illuminate the importance of cemented property for the bearing capacity of the sandstone structure, which provides a scientific base for research on the failure mechanism of the sandstone under special conditions. Therefore, the above numerical method is more efficient and applicable for comparatively large scale and complex experiments, and the obtained research results can bring a new thought for the real cemented sandstone to research on its macro-micromechanical response and the structure failure mechanism, and also is significant for the sand production mechanism, sand volume prediction and sand control measures for the sandstone reservoir.