The deformation micromechanics of single-walled carbon nanotubes in a polymeric matrix was studied through the use of Raman spectroscopy. The variation of stress sensitive G' band positions was used to detect the interfacial adhesion between the nanotubes and the matrix when the composites were subjected to a cyclic deformation process. It was found that the level of the interfacial adhesion decreases with the maximum loading strain and the repeated loading cycles. The debonding phenomenon was saturated by the third cycle of loading of the composites up to 1.0% strain. A hysteresis loop was observed to develop due to the change of the stress transfer efficiency between the loading and the unloading steps when the sample was deformed over 0.4% strain. By analysing the loop area, the energy dissipated in the deformation of the composite materials was investigated and the extent of the interface damage was also assessed.