Abstract This paper presents an analytical model to describe the influence of mechanical deformation on the effective electrical conductivity of CNTs reinforced composites. The model shows that the effect of mechanical strain on the effective electrical conductivity of CNTs reinforced composites are via two mechanisms; one is the strain-induced alteration of volume fraction of inclusions and the other is the strain-induced change of the tunnelling electrical conductivity of inclusions. Analytical formulations are developed for calculating the dependence of the effective electrical conductivity of the composite on the mechanical strain. The model is validated by using experimental data published in literature for CNTs reinforced polymer composites.