A micromechanical model based on the realistic microstructure of carbon fiber reinforced aluminum (CF/Al) composites was developed for the first time. The transverse compressive behaviors, with particular emphasis on damage mechanism of the composites were investigated by numerical simulation and experiment. The results showed that the micromechanical model considering the realistic fiber arrangement predicts the mechanical properties more accurately than that based on an idealized fiber arrangement, and the calculated stress-strain curves agrees well with the experimental ones. The interfacial damage accumulates with compressive strain increasing, and induces the local interface failure successively. The progression and interaction of interface failure and matrix damage dominates the transverse compression process, and leads to the initiation of fiber failure in the ultimate stage, resulting in a fracture surface with the characteristic of interfacial debonding and fiber rupture. Moreover, parametric analysis based on the micromechanics model was carried out to evaluate the influences of interfacial properties and fiber volume fraction on the transverse compressive behavior of the composites.