Abstract: The single lap joints with different overlap lengths were fabricated by titanium alloy/aramid fiber composites, and their tensile strains and ultimate loads were characterized by DIC and universal testing machine. The effect of overlap length on the bonding properties and failure modes of the single lap joints of dissimilar materials was investigated. The results indicated that the ultimate load of single lap joints increased with an increase of overlap length, but their bonding strength decreased. The joints of high overlap length were damaged progressively. The joints rotation caused by the eccentric bending moment decreased, and the proportion of longitudinal strain area in overlap region was also reduced. Moreover, the fiber?tear failure of the composites increased, but the adhesive failure between the titanium alloy and adhesive layer decreased. In addition, the layer number of the stripped composites increased.