The uniaxial compression test was carried out on the materials specimens with similar parallel-cracks and it was simulated using the PFC3D model. A failure mechanism study of jointed rock with parallel-cracks was discussed by comparison of uniaxial compression test and DEM. The results showed that: at the deformation and failure stage, the“double peak” phenomenon appears in the stress-strain curve when the axial strain reaches 0.02. The uniaxial compressive stress varies nonlinearly with the increase of the pre-existing cracks dip angle. When the pre-existing cracks dip angle is no more than 45°，the uniaxial compressive stress does not change significantly with the pre-existing cracks dip angle. The uniaxial compressive stress of specimen with 45° pre-existing cracks dip angle is lowest. The uniaxial compressive of specimen increases with an increasing pre-existing cracks dip angle when the pre-existing cracks dip angle is larger than 45°. The range of crack initiation is located in the middle of the two pre-existing cracks. With the pre-existing cracks dip angle increase, the crack initiation position extends from the end of the crack at the middle of the pre-existing cracks to the end point is located at the other end of the crack at the tip of the pre-existing cracks，and finally transform to both ends are the crack tip. Different pre-existing cracks dip angle of the specimens corresponds to different ligament angles. When the ligament angle is large than 60°, it is positively correlated to the uniaxial compressive stress.