The mechanical responses of CNTs (carbon nanotubes) and aluminum matrix in the process of plastic deformation of CNTs/Al composites are complex and interact with each other, so it is difficult to systematically and deeply reveal the mechanism of the formation and development of microstructural damage and its influence on the macro mechanical properties. Numerical modelling of the deformation process of composites can economically and efficiently study the influence of various microstructures and external factors, to further achieve accurate prediction of damage behaviour. In this paper, first, the widely used continuous damage model and cohesive damage model are introduced, which are suitable for describing the deformation and damage behaviors of composites under different conditions, respectively. Then, a representative volume element model suitable for multiscale modelling is introduced, which can consider the influence of structures with different scale characteristics on deformation and damage.