<p>The interface between cemented tailings backfill (CTB) and rock is commonly encountered in backfill mining, and the CTB-rock interface play a crucial role in determining the strength requirements of the CTB and maintaining the stability of the mining stope. In this paper, the effect of interface angle, interface geometry and cement content on the mechanical properties of the CTB-rock specimens under triaxial compression were investigated. The results revealed that the angle of the interface and principal stress significantly affected the shear strength of CTB-rock. As this angle increased from 0° to 60°, there was a transition in stress–strain behavior from strain hardening to strain softening. For specimens with the identical angle, increasing cement content improved bond strength while maintaining an almost unchanged internal friction angle. The effect of sawtooth on strength was found to be dependent on sawtooth width. As sawtooth width decreased, the failure pattern shifted from sliding to shear failure and eventually to tensile failure in the CTB matrix. The peak deviatoric strength initially increased and then decreased with the decrease in sawtooth width. Finally, theoretical calculations indicated that as confining pressure increased, there was an elevated risk for shear or tensile failure in the CTB matrix but reduced risks for sliding failures on the CTB-rock interface. These research findings are expected to provide systematic experimental support for developing comprehensive models describing different roughness and inclinations in CTB-rock interfaces.</p>