The article aims to investigate elasto-plastic nanocomposites damage behavior dependence on the interfacial bonding between metal and ceramic phase. To this end, a unit cell representative volume element and cohesive element model were developed numerically to simulate matrix and reinforcement phases and the bonding between them. Through experimental study, commercial pure Al and Al2O3 are used as raw materials to produce Al–5%Al2O3 nanocomposite by using high energy ball milling followed by cold compaction and sintering. The developed model with cohesive interface elements is validated and approximately it is identical with experimental results available in the literature and others done during this work for Al–5%Al2O3 nanocomposite. Numerical results show the validity of representative volume element with cohesive elements model to accurately simulate the stress-strain behavior of nanocomposites which highly reduce the computation cost of 3D models and binarization errors for simulating real microstructure. The results show that the interfacial bonding between ceramic and matrix phase has a large influence on the prediction of the stress-strain behavior which highlight that the assumption of considering fully bonded interface in the simulation of nanocomposites is inaccurate. The ultimate interface strength is the most critical parameter that affects the decohesion behavior between matrix and reinforcement nanoparticles which makes the bonding between these two phases a critical issue in production of nanocomposites. This highlights the immense demand of finding new methods to improve adhesion between reinforcement and matrix phases for production of nanocomposites with improved properties.