Abstract: During the transition from open-pit to underground mining operations in coal mines, investigating the mechanical characteristics and deformation-failure mechanisms of cemented paste backfill-rock (CPB-R) composite structures holds particular significance for ensuring underground stope stability and preventing rockburst disasters. Numerical simulations using the rigid body spring network (RBSN) method in PFC^2D software were conducted to analyze the failure behavior of CPB-R structures with varying interface inclination angles under uniaxial compression. The influence of interface inclination angles on strength characteristics, failure patterns, and acoustic emission (AE) features of CPB-R composites was systematically explored from macro-meso perspectives, with experimental validation provided by laboratory uniaxial compression tests. The findings reveal that the strength of CPB-R composites exhibits a “U-shaped” trend with increasing interface inclination angle, reaching the minimum peak strength at approximately 60°. When the interface inclination exceeds 30°, the yield stage of the stress-strain curve weakens and the brittle characteristics increase significantly. With the increase of the interface inclination, the failure mode of the CPB-R composite shows an evolution trend from “Y-shaped” failure to interface slip failure and then to mixed failure. The ultimate bearing capacity shows a transformation from being controlled by the filling body to being controlled by the interface. It then transforms into an evolutionary trend controlled by rocks. With the increase of the interface inclination angle of the CPB-R combination, the degree of interface failure keeps improving. Interface damage will prevent the further sliding of the interface (interface inclination angle <60°) and lead to the occurrence of tensioning failure. The rock burst index （K_E） first decreases and then increases during the process of increasing the elastic modulus ratio of the filling body to the rock. Controlling the elastic modulus ratio of the filling body to the rock within 0.4-0.5 can effectively reduce the risk of rockburst.