Abstract: Triaxial compression testing was performed on an MTS 815.03 rock testing machine and acoustic emission data were collected by using a DISP acoustic emission test system. An experimental comparison was done between rock mass specimens having a weak structure plane with steep dip angle and rock specimens. The strength of the two kinds of specimens gradually increases with the increase of confining pressure, and the failure mode changes from brittle to ductile. Sliding failure along the structural plane occurs in the rock mass, while shear failure in the rock. With the increase of confining pressure, the elasticity modulus, deformation modulus, peak strain and peak strength of the two kinds of specimens increase. Moreover, the elasticity modulus, deformation modulus, and peak strength of the rock mass are lower than those of the rock, but the peak strain is higher. The internal friction angle of the rock mass is lower than that of the rock, but the cohesive force is higher. With the increase of confining pressure, acoustic emission events in the peak stress stage are far more than those in the other stages, and the acoustic emission events of the rock mass are more than those of the rock. The results of study show that the weak structure surface results in the lower mechanical properties of the rock mass, so it is a key factor in site selection for a high-level radioactive waste geological disposal repository.