Abstract: To investigate the stability of composite structures with initial damage,this study combines uniaxial compression laboratory tests and discrete element numerical simulations to analyze the mechanical properties and energy evolution patterns of fiber-reinforced concrete-rock composites containing cross-shaped fractures under different cross-shaped fractures ranges and angles. The study concludes: in laboratory tests, the stress-strain curves of sandstone, fiber-reinforced concrete, and the composite exhibit four distinct stages, with their mechanical performance differences stemming from material properties and structural characteristics;Numerical simulations revealed that crack propagation patterns correlate with the angle and interface constraints,while compressive strength and elastic modulus exhibit nonlinear variations. Energy analysis demonstrated similar energy evolution curves,reflecting the energy transformation process from complete to broken in the composite. Furthermore,a damage constitutive equation was established using the damage factor D,derived from the crack length ratio and angle,providing new theoretical references for studying the stability of damaged composite structures and expanding research on the mechanical behavior of composite structures under complex cracking conditions.